Started playing last night. The defending is incredibly challenging, sometimes the opposition just waltz through you and your defender bounces off of them. Trying to call a second defender over can help sometimes but it can also lead to a disaster when they bump each other and go flying thanks to the physics engine. I suspect they will be fixing this soon in the first patch.
I was playing with a 71 keeper in goal and every time he rushed out he couldn't get a hand on the ball and gave away a pen, so be wary of that. Also, if your keeper gets sent off and you don't have one on the bench then he walks off to the side and gets stuck for a minute or two before the game realizes whats going on and then he comes back in goal for the penalty...weird one that.
Attacking-wise the game can be pretty frustrating. As the IGN review said, if you like crossing you should get PES because they have just completely removed any ability to either put a decent cross in, or in the event that you do, have the ability to actually power a header at the goal. The only header I scored come off of a corner, some of the crossing was woeful. With that in mind, you can play some of the most ridiculous impossible through balls I have ever seen right through the middle of the midfielders and defenders with nobody intercepting them. At one point I think Besic played a 70 yard through ball right through 4 players for Eto'o to magically run on to. I'm not a big fan of what they have done with the team management/squad selection menus, they are slow to react(On PS3) and require a lot more button presses to get into the reserves and make a switch.
I enjoyed some aspects of it but really disliked some others, overall it is decent enough like.