Looking at the screenshots it looks a lot like Unreal 2. So I expect performance to be @ or slightly worse than Unreal 2. It doesn't look like a massive leap forward graphically. And with the ability to toggle some options I think that most mid-range systems should run it fine.
I find that Unreal2(xmp) runs better on my Geforce 3 Ti 200. I even had my Celeron with its massive 1MB of ram onboard video play it. Even though I was getting around 2 FPS.