I think it's a great game too. The total punch control is a great dynamic and it becomes almost second nature after a little time.
That being said, I'm not a big fan of the"Knockout moment" where everything slows down and everyone knows that one guy is hurt. It just becomes a game of chase me, chase me, instead of having to guess if your opponent is hurt, and if you should go for the K.O. I'm also a little miffed at the blocking/countering system because it's a bit weird. If you block my haymaker and I'm left off-balance for a bit that's understandable. However, if I flick a jab out there, you shouldn't be able to throw me all out of whack by blocking it leaving me stunned for a few seconds. In the championship level fights, The computer uses that tactic whenever you've got the upper hand and it gets to the point where you just can't get off first cause he'll counter/block whatever you throw (leaving you stunned) and tag you with three quick haymakers. Somewhat frustrating.
I've only played it online a handful of times and there was just enough lag to turn me off. You can see a punch coming, but the slight lag reacton time won't always let you block or slip it. It also bugged me that you have a different online control/profile than when you play the single player. I've set my player movement controls differently than the default in single player, and when I played online using my profile, I couldn't understand why I was having such a hard time running away or closing the distance and go for the knockout. My controls were reset to the default in my "online profile".
But all in all it's a great game especially when playing with friends who know what they're doing. Some fights really do become all out wars with the tide turning round by round. My buddy and I even created makeshift versions of Rocky Balboa, Ivan Drago, Apollo Creed, and Clubber Lang. Good shit!