Dude... do you get serious lag spikes? It doesn't seem to affect the ps3 but my gf's brother was complaining to me that he was getting serious lag last night on his 360, like it would skip about every 4 seconds or something.
Is that the kind of problem you're get? He went out and I tried it later on and it seemed fine but I'm guessing its a wonderful inconsistent problem.
I will answer as if you are talking to me,
No I do not get lag spikes all the time, only when people leave/join a game in Black Ops (this is the main game I play online) and also people just get kicked out of the game I am in.
It's not an inconsistent problem at all sadly,
take last night for example, it found one game for me join, I backed out and then tried again it found 43 games, then coutned down to one and wouldn't let me join the game.
The service is a joke.
shame I am contracted until Jan 2012.

It's depressing even talking about it, I may as well not even bother having an internet connection, as I cannot use it for gaming on my 360.