I've got a PS3, and I've played online a few times but the basic problem is one that maybe can't be fixed. I'm 28 and with a job and a baby only manage to find 2-3 hours a month to play. I've played about 10 online matches of the new UFC game, and the best result so far is surviving to 3:43 of round one, and landing about 6 shots.
Unfortunately, I'm also good enough at the game that playing multiplayer at home with friends, I can way too easily beat them without trying. Against friends, I intentionally let people back up from the ground, and don't counter every transition if I'm down etc. but I really have to try to lose for it to ever happen.
The situation generally seems very much the same across all the games for the PS3. Playing online, I get my ass kicked to the point where it's just not fun. Against friends, I can kick their asses to the point where it's just not fun.
By comparison, my brother brought round his Wii a couple of weeks back. I actually won one of the games of bowling, and tennis wasn't completely one sided either. I've never enjoyed playing any game on the PS3 as much - unfortunately, it was just the wrong choice for someone in my position. I'm now getting a Wii and I suspect it will get used a lot more than the PS3.