Played the demo on the Xbox and it has some cool moves in it but i would rather have played it with my keyboard and mouse, the mark and execute works great, but due to it being on console demo the aim did not have to be perfectly alligned with the targets head for a headshot, so that makes me even more hesitent on getting it for Xbox rather then pc besides the issue with controller vs mouse keyboard.
Always plan'd on getting it for the pc, however the new drm they are using for pc can be a bit demanding on the internet connection and the few issues i have had with connection loss with settlers 7, server dropped me off a few times in march.
I personally only play games on PC, reason why is because you can do so much more with a PC game then a console game. I'll give you one game in particular GTA San Andreas. I totally moded that game, no vehicle in that game looks like it was originally released. I had real car names and real car looks to it. In Double Agent I found a way to change and make any weapon in any way that I wanted. I hope Conviction is based on the same interface, or similar at least so I can edit the game and mod it my self.