I think the problem is not that the game isn't better than previous versions - it clearly is - it's that apart from player animation and a few new features, there hasn't been much improvement at all. My main complaint, is that the AI remains stupid. Off the ball player movement, is just awful. Unless i'm not applying features i don't know about..
To me, this is like a mix between the previous version and PE6.
To me, PES09 is PES09, for me it isn't better than either PES5 or PES6. In fact, it actually amazes me that some people claim it is better.
Personally, when I play PES09 I Think Less -then- when I play PES6. For me PES09 is easier, I'm not going to say it's better or worst, but for me it's Easier.
I think the Attacking AI has improved as I have noticed that the Strikers move better now, but the Defensive AI is just ridiculous, it Looks and Feels like a bunch of kids running relentlessly after the ball.
The Attacking off-the-ball movements are quite good, but the off-the-ball Play is very very poor. To put it simply, there is no off-the-ball play.
We simply decide How and When to Shoot or Pass the ball, whilst the Com Dictates everything else.
And like you said, the game just doesn't offers anything New to master, there's not One Revolutionary and Significant feature in PES09. It's just the same Old, but even more simplified.
After PES5 and PES6, I was very interested in How the PES series would "evolve" along with Next Gen Consoles. But today I'm not looking forwards to PES 2010.