Even though this game's UI and other user-interactive stuff will be designed for consoles (for controllers), in most cases, it's still better to play these games with mouse/keyboard. It's more fluid, fast and rapid. You simply play the game better.
I suggest you to buy new PC before this game gets out, if you can afford it of course. But if you don't plan to buy PC for any reason, don't buy PS3 either. If you have ever read EuroGamer's 'Digital Foundry' articles which compare PS3 and X360 graphics, the result usually is that PS3 version of multiplatform games runs worst. They look slightly worse (blurry textures, more pixelated shadows etc.) and run little slower in most cases. The different is barely noticeable in fast gaming session, but you can definetly see the dramatic framerate drops which PS3 has in many multiplatform games. I'm not here to flame anyone, but I think you've just heard some PS3 really devoted fan talk about how their gaming device is so godlike. PS3 has BluRay, but other than that, X360 over PS3 imo.
Like someone said above, this forum is so nice, because here seem to be very smart and polite people writing and reading. Me like