I have very small experience on PES to make comparison, i've been playing Fifa games for as long as i can remember and just played PES a few times last year and many times 2 yrs ago (a jap version, WE actually).
Overall, i am much happier this year with the demo than i was for the past few years. The atmosphere, which is a very important element which actually gets you in a footy mood, is superb. Never saw / experienced nothing like it. I pushed my jaws back up and started playing...
I lost bad on first games, not useed to keyboard and new controls, but i enjoyed it, as the AI worked impressivly good with Shevchenko and Crespo doing stuning things in my box... then i got a yellow card and as i was home team, crowd almost blusted my speakers !
When i started to get a grip on it, the game started showing what it could do. I've done manouvres and passing never seen in previous games, Henry tiped the ball over his head to pass to him self (but failed to score then), Shevchenko (in my box) had a aheader which was bloked by a defenders head while diving... and many more to remember. And compared to older games, where goals were scored with about the same way all the time, the game play is, Yes, muuuuuuuch better.
Enough, i'll go play some more