Pretty solid fps. Merging of cs and tf2 it seems. Gameplay is fast and the guns are responsive. Only annoying this I've found is that you can't change between more than 3 of the five(?) classes during a match. Maybe this makes sense if your team is coordinating what classes they're going to play, but it seems odd for the average pub.
The sniper class is pretty legit. He might actually be over powered, because he seems to be able to go 1v1 with ever class at close range with his smg, and the sniper rifle takes players down to really low hp on body shot, and instant kill on hs.
Playing sniper earlier to day I was able to go 17/3. So either I'm a sniper god or it's op. I'm gonna go with the latter...
Anyways, I think this could be a really great arena shooter. I doesn't exactly have the finesse and simplicity that tf2 has, but it's definitely good.
Also, I see people talking about how the shot gun/scout class aren't viable, and this is mostly true. I played a few maps which had crazy flank routs, and was able do do very well by sneaking up on people. But I think the use of the scout class is going to be very map dependent. On wide open maps with very few flanks, it's utter shit.