Just finished most of the demo content. Holy shit, I played all the other games on 360 but it looks really damn nice on PC. Lots of shiny shaders and general crispness. Ran without a hitch, just some very quick texture LOD pop-in when jumping back a long distance with the restart button.
The FMX trick stuff seems really well implemented - about as good as I could expect. It feels very balanced and natural, as they've said a lot, it's all physics based. I can see myself putting quite a bit of time into it, when I'm not banging my head against extreme platinums. Now I'm really hungry for more as the beta only includes easy tracks.