It actually feels really pleasant on the PC, it says press space instead of press Y, like in Assasin's Creed and there is mouse in menu.
I heard skidrow managed to hack it and you can play on LAN, hamachi comes in handy.
There are perfomance issues, for many out there, game is slow, even with GTX 275 and i7. There are patches on the way.
AI is superb and the new Last Known Position is great, for me it is 9/10 game as it is, if the FPS improve it will definetely be the best Splinter Cell up to date.
i5 750 normal clock
GTS 250
4GB DDR3
P.S. Looks like UBISOFT appreciate that PC players made Splinter Cell what it is now, and they developed an amazing game.