It ran quite bad the last time I tried it (its been a while though, and maybe it was just teh bloom). I didn't like it back then because the weapons didn't make much sense to me. Its ok when weapons look sci-fi but you should still be able to develop a general idea of what it does, just from the look of it.
Do you know Pariah? Every weapon looks like a sci-fi pack of cornflakes and one turns out to be a grenade launcher, the other is some kind of shot-gun, etc. I don't like that, but tastes differ.
Also I didn't like Nexuiz' feel. It felt like a mod who tries to be Quake.
As I said, its been a while and it was pretty early after its first release (or was it beta?) so I might give it another try. Maybe its better now, and maybe it was never as bad as my aforementioned impressions...
Are there working bots now?