Based on my demo experience, I am overall content with the game, but there is one thing I can't get for christ's sake:
Penalties.
I dunno if it's some kind of weird joke or if the programmers were on coke for this part of the game, but I have not been able to score a goal from any of my penatly attempts so far. Hell, I wasn't even able to release a decent shot. Two went straight in the middle of the goal and the third one went only 'a bit' (read 5 meters +) away.
Computer, of course, has no problem with penalties so basically, if you play a tied game and know that penalties will follow, you can consider your game a loss.
People seem to dislike the penalties in the previous PES games as well, but when I compare the current penalties and the previous, I'm starting to love the older ones.
I dunno if it's just me and the penalties are the same as they were in the older games, but I personally take them as the most screwed matter in an otherwise good game.
As for refs - yes, they're freaking sensitive. If Konami ever makes a basketball game, they can use the refs from PES 2011 there.