I was playing a game with the Yor in an immense (biggest) galaxy with the AI on tough.
Several things bothered me:
1) Again and again during planetary invasions, I lost to the Krynn even though I had superior forces - especially when they invaded my planets. Example: I would have a soldiering rate of 35, a tech rate of 545903, and 4500 troops, the Krynn would hit me with 2000 soldiers with a soldiering rate of 21, a tech rate of 441448 and would win with less than 50% losses! This happened over and over again.
2) I was the highest tech empire for 2/3rds of the game when suddenly all my tech started costing a FORTUNE! My lowest techs (like armor defense which I hadn't researched at all) took 5-10 turns even with production set at 75% and research at 40% - I had several research planets with a planetary value of 17-20 with 15 of those tiles being invention cities - plus research matrixes and invention cities on most other planets (1 RM and 1-2 IC per planet).... ?!?!? Suddenly my tech was taking forever where before I was easily the highest rated civ in the universe....
These are the 2 biggest things that bugged me - but I will go back and reflect on the game some more.... I gave up about 1/2 way through the game so I could start a new one and monitor it more carefully.