I was able to connect over the last test from the US on the shittiest wireless internet you can imagine and I didn't suffer any serious gameplay issues. There were about 4 of us all together (to highlight the fact I was around other people, not the amount
P) and no one was sliding or stuttering. The game was smooth and responsive.
I can't comment on how it's affected by a whole mess of people, but generally I slide around the screen in empty servers in other games with this connection. (thankfully, it's my last week here on this horrid connection!)