I played the demo on PS2. Not before wasting 3 DVD in the process.

The demo finally worked in the 4 th try. It was designed to work on a CD and my playstation doesn't read Cds anymore so I had to convert it and something was missing every time.
Graphics :
It's the same graphic engine since PES 4. No surprise here, the PS2 reached its limits and the graphical quality cannot be improved further without ruining the gameplay or the fluidity.
I really like the work on faces from Konami, the licensed faces look awesome. They improved the lighting effects and the faces have a small glassed effect on them. (next gen effect guaranteed ), same about hairstyles : unlike PES 2008, now every licensed player has his own (top quality) hairstyle. Ribéry& Toni looks awesome. The kits were improved as well : they have this HD style with the folded effect on them. It would be very difficult for kit makers to reach this quality on a small texture (512*256).
Gameplay :
The game is much more difficult. In the first game I was completely dominated with only 35 % in possession !

It's a weird thing but the 4 difficulty was much easier to me than the 3 rd one, I think it's justs fits my style of playing. In this game you don't have much space, the AI is superbly occupying the field and the pressing is fierce. You have to be as much creative as possible to beat the defense. Goal keepers are very good (not sure if it's a good thing or not) maybe too good. With Toni I remember that I wasn't able to beat J.Cesar even on a very close range powerful shot. Of course we shall eventually find the weaknesses of the AI with the time. It's much more difficult to shoot from distance, and the shots aren't too deadly anymore. Basically : It's a more challenging game in all aspects and from what I've heard the gameplay on PS2 will be more likely the best in all platforms.
Content :
The Champions League isn't featured in the PS2. A vicious move from Konami to turn the PS2 users on next gen platforms. Well it's not a major issue because the teams weren't all licensed. The balls, the menus, the intro music, all of this could be manually added in our DVD.
Global impression :
This year PES 2009 looks very promising, I hope that the final game confirms my good impression on the demo. This year we won't have an unfinished game like the previous one, the release date is set to the 31 October. I hope that they're still working on the game and this delay isn't justified solely by marketing/commercial reasons. One more time we shall rely on editors to take the game to a next level and deal with the unlicensed teams and the poor textures of stadiums.