I won't go into the "Next Gen / Current Gen" politics: But I still think that instead of doing all this work on the old engine, they should have just ported the 360 version already.
After playing the PC demo, I am very impressed by the menu system and intro compared to Fifa 08. Intro is now in proper widescreen, for widescreen displays and looks sharper.
Gameplay is improved from Fifa 08. But only in small areas such as in collisions and the shooting force from outside the box. The gameplay still feels too much like Fifa 08. It definitely doesn't come anywhere near as fluid and realistic as PES. The biggest let down is the ball physics. I don't know how to describe the ball movement, but it doesn't feel like you're playing with a football.
Graphics: Slight improvement on 08. I was expecting better, considering all the hype over the graphics.
Player models look horrible: like robotic moving zombies with big veins and dead skin and strange sinister eyes. To be honest, I have never been a fan of the way EA Sports create their players, even on the Next Gen versions. They said the players on PC will be the same as console versions, but that's not true. They still use the same robot looking frame from Current Gen and then paste the XBOX zombie-like details onto it. But the PC players look even more dead than the XBOX version. The foreheads shine like they are made of plastic (it's supposed to be sweat). PES 2008 player models are much more animated, detailed and human like.
I'm not impressed by the 3D grass. It's too tall zoomed in and it doesn't look like grass, especially when zoomed out.
A good point is that the ball seems "slightly" smaller than in Fifa 08 and not so super sized.
Replays are much sharper than Fifa 08.
Conclusion: I won't be buying the full version. I know that full versions usually have better visuals and gameplay than demos, however, the demo is too far behind PES 2008 to have even the slightest chance of making a difference. That's without taking into account the improvements for PES 2009.
Gametrailers.com - Pro Evolution Soccer 2009 - UEFA Champions League Trailer HD
Gametrailers.com - Pro Evolution Soccer 2009 - GC 2008: Seabass Interview HD