I started playing a fast-paced, small map game as the Shadows, against the Golems, Undead and Centaurs, and it's running incredibly smoothly, with the four races closely balanced (there's a 20 point power gap at the moment between the Centaurs, who are strongest, and the Undead, who are weakest). I love the way the Shadows look and play and haven't encountered any problems with them.
The other races are performing strongly too and don't seem to be having any troubles I can see. The Centaurs have been dominating throughout and easily conquered the darkling wildland city Deorcnysse, which is right on the edge of my territory. I'm about to go to war with the Golems, so I'll find out more about what they're capable of soon, but they seem to have built up three very solid cities and have massed some strong troops. I know least about the Undead as I haven't been able to get far into their territory.
The only bug I have seen is that on the diplomacy screen the Centaur sovereign seems to be missing his lower body - his head's somewhere near the bottom of the screen rather than the usual height when I talk to him.
I was hoping to get a look at the new injuries & give some feedback, but no Stormworld champions spawned near me, just men and fallen - I'll have to see if any of my rivals managed to recruit one.