It's not exactly a PC game, but this seems like the best place on these forums to put this
Note: This is intended to be a discussion about the game, not about how PC's are better than consoles or about how Halo sucks (if you think it sucks and have a valid reason, that's fine, go ahead and say it, but please, no "Master chief is teh gay and suxorz and stuff!!!1!1!").
So anyway, with that out of the way, here are my thoughts on Reach.
Graphics: Quite simply, I was amazed at how good Reach looks. Yes, it's a console game, and no, it doesn't look as good as it could on a PC, but for a 360 game it is gorgeous. The previous games made you backtrack through the same locations a lot, but Reach pretty much avoids that. Every area is new and looks great. The cutscenes are excellent. Overall, it looks very good.
Sound: I've always loved the soundtracks for the Halo games, and Reach is no exception. Martin O'Donnell and Michael Salvatori are amazing composers. The music does an excellent job of setting the mood of a losing fight. The general sound effects are good too, but it's the music that really gets me.
Campaign: Honestly, this is the reason I bought this game. Multiplayer is great and all, but I suck at it and generally only play it with friends (plus Xbox Live is famous for its twelve year olds). Single player is where it's at for me (or co-op). If you're still reading this, and the "[Spoilers]" in the title didn't alert you; consider this your final warning. Now, if you're the least bit interested in Halo, you probably already know the story of Reach, even if you haven't read the books (I never read any of them). The Covenant attack Reach, the humans try to mount a defense, the defenses fail, Reach gets glassed, and everyone dies. This is probably the greatest shortcoming with the story; you know how it will all end. It's hard to make the story compelling when you know it all ends up being pretty much pointless. Bungie made a good effort at it, but there were times where I was thinking "Why do I have to bother doing this, we all die at the end anyway?" That could've just been the frustration at dying over and over, though.
This brings me to the next thing about the campaign. It is much harder than the previous games. Although it has been a while since I did the Halo: CE campaign. It's definitely harder than Halo 3 or ODST. By far the biggest factor in this is the Elites. They are back to their original position as the ultimate Covenant unit and not the crappy upgraded-marine support they were in Halo 3. The Elites are tough, really tough. The Halo games have been known for their excellent enemy AI, and Reach is no exception. There are definitely some improvements over the previous games. Sadly, however, the same cannot be said for the allied AI. The marines still run right into fights they can't win, and they still refuse to take cover and just stand there and get shot. Reach introduces squads, where if you get close to a marine, he will join your squad and follow you around, and you can have up to five marines in your squad. In theory this should alleviate their dying somewhat, but (and this was on Legendary) they still do stupid things. Basically, having a squad is worthless, because they all die almost instantly (maybe on normal or easy they might be useful). In some missions you get a partner in the form of another member of Noble Team. Most of the time, they are pretty much useless. One mission partners you with someone with a sniper rifle, but he refuses to use it to snipe. He'll go in for close range and then try to use it like an assault rifle.
But I was talking about the difficulty. Health from ODST is carried over to Reach, and this is a big factor in the difficulty. For example, a fully charged Plasma Pistol shot completely takes down your shield and slightly damages you. But with the plasma shot, the health you lost will after a time recharge with your shield. But if you're already low on health, even if you have full shields, a charged shot will kill you (on Legendary). It will infuriate you to no end when a Jackal kills you with a damn plasma pistol just as you're about to get to the end of an area.
Now, a couple of things that bugged me about the campaign. Mind you, these are small things, but they bugged me nonetheless. First, Grunts (and the other Covenant) don't speak English any more. This isn't really a problem, but the game loses a bit of its charm because of this. In the previous games, the Grunts were collectively one of the most hilarious characters in the game because of the stuff they said as you were about to kill them or something. In Reach, you still get the funny visuals (I love it when the things on their backs come off and they fly around on leaking methane) but it's not the same without the grunts asking you if you want some methane right before you bash their heads in.
The next thing is that at the times the game encourages, if not outright telling you, to run past difficult obstacles. In a later mission (7 or 8, I think) you are tasked with deactivating a bunch of radio jammers across the city. One is guarded by four hunters. There is very limited ammo, and you have no backup. It's damn close to impossible on Legendary by yourself. It ends up being much, much easier to just run past them, deactivate the jammer, and run away. Even though you see a lot of Scarabs in the campaign, not once do you take one down yourself. Two you are explicitly told to drive past (granted, given the story it does make sense, but still, I would have liked to take one down). A third Scarab is taken down by Noble 1 crashing his Pelican into it.
This brings me to my next irritant. The members of Noble Team are picked off one by one. It's what I expected would happen, but it's kind of clichéd. The first, Jorge, dies when the timer on the bomb to blow up the Super Carrier malfunctions and needs to be activated manually. Seriously? Didn't see that one coming. Kat is the next to die, with by far the lamest death. Walking through a burned out building; gets sniped in the back of the head. After all the crap Spartans can go through, one measly Needle Rifle shot goes through her helmet? The commander, Carter, crashed a Pelican into a Scarab, as I already mentioned. Emile goes down fighting two Elite Zealots, and takes both of them with him. And make sure you don't skip the credits, because there is a final "mission" that reveals what happened to Noble 6 (you). You get surrounded by like ten Elites, and die taking them all on. You'll notice that this list is missing one member. That is because the game never reveals what happened to Jun. He separates from the rest of the team and is never heard from again. I was kind of surprised they never said what happened to him, but otherwise it was kind of predictable.
One awesome thing that was added, and showed off a lot at E3, is the space combat. The mission is about halfway through the game, and it is pretty awesome. It works very well, much better than I would have expected considering that it is an FPS. It would have been nice if the space combat part of that mission was longer, and if you got to be the part of a large battle as opposed to mostly just dogfighting with Covenant fighters, but still, it was a lot of fun.
EDIT: One thing I forgot to mention. There is no Flood in Reach, which helps the campaign immensly. I hate the Flood in the previous games; they were by far the worst part of the campaigns. It's really nice to not have to face them.
Overall, I think the campaign was very good. It has some issues, the biggest I think is the fact that you know how it will end, but it was still very fun. It was shorter than the campaigns of the main trilogy, but longer than ODST. It borrowed some story telling ideas from ODST, which I think made it the best story of the series, despite the shortcomings.
Multiplayer: This is probably the reason most other people bought the game. I haven't done it nearly as much as I have done the single player, but I've done a bit. Co-op on the campaign works just like the previous games, not much to say there, although it is worth mentioning that parts of the campaign are almost intended for multiple people, and the enemies scale as you add more players. I haven't done much of the normal multiplayer, so I can't comment on it much, but it is very fun. It's what you would expect of Halo multiplayer, but with even more polish than the previous games. Definitely my choice over Modern Warfare 2.
Firefight from ODST makes its return, but vastly improved. This is my favorite multiplayer mode by far. In ODST it was basically; get some people, choose characters, and go, but Reach adds so much more. You can customize almost everything. What enemies show up in which waves, what their weapon loadouts are, which skulls are turned on/off, and a ton more. I haven't even had a chance to touch most of the options yet, because just the default is that fun. In default, it plays pretty much the same as ODST, but with a few minor tweaks. You choose a "class" at the beginning and every time you die, which gives you a specific set of weapons and a certain armor ability. There is now an ammo locker where you start (and possibly in some other locations depending on the map) that refills your ammo for your starting guns, but not any that you pick up. As long as you don't change weapons, you can continue to get ammo. Additionally, there are supply drops that provide you with the most powerful human weapons, the rocket launcher, sniper rifle, Spartan laser, and the target designator. The target designator is a ton of fun; it allows you to call down an artillery strike. In my opinion, it is the best mode if you and a couple friends just want to kill some alien scum without the customary trash talking and competitiveness of playing against each other.
Closing Thoughts: Overall, I think Reach is excellent. I would give it a 9.5/10. Despite a couple problems, the single player campaign is good and multiplayer is obviously amazing from what I have played of it. I would even say it is one of the best FPS's out there, for any platform, although I realize many PC gamers will disagree with me on that point.
The achievement for completing the last mission of the campaign is called "Send Me Out... with a Bang," and that is obviously what Bungie tried (and I think mostly succeeded) to do with Reach. It is Bungie saying "goodbye" to the Halo universe, their creation. Whatever other people may think about Halo, I think it is rather sad that we have reached (pun not intended) the end of an era. It's hard to believe that it has been almost a decade since Halo: Combat Evolved came out, and like it or not, it has had a huge effect on gaming in general.
Going forward, I have two wishes for the future of the series and the future of Bungie, but sadly, both are unlikely to happen. The first is that Microsoft sits on Halo for the next ten years and doesn't do anything with the franchise. Any future Halo games won't be the same without Bungie developing them. But since Halo is so profitable, and Microsoft has already set up 343 Studios to take over, I doubt they will leave it alone.
My next wish is that Bungie escapes Activision unscathed. If Bungie ever returns to Halo, it needs to be the same Bungie, but considering they have a ten year contract with the devil, I don't see a lot of hope for this either.
But whatever the future may hold, Bungie wanted to go out with a bang, and I think they did that.