There is very limited lag. The only I experience while playing is subtle frame rate hitches when it gets intense on Domination (the 256 player mode) in the middle. And some players just have down-right terrible connections, so one out of 500 people might lag to the side a little bit. Other than that, no lag.
I'm Quiksiiver_ playing as SVER (the best one for sure) level 34 now? idk. It's fun though, try it out.