I've captured portions of Extraction's first level, as it is rendered on the PlayStation 3. The game didn't look that much rougher on the Wii and, as far as I'm concerned, is attractive on either system, thanks in no small part to strong architectural art direction and excellent camera work. The game is almost entirely on-rails, so think of it as a glorified light-gun shooter. I guarantee, though, that you won't feel like you're merely in some pop-up shooting gallery should you play the game. You control it with a PlayStation Move, which behaves much as the Wii Remote did.
(I haven't tried it, but I'm told you can play Extraction with a regular PS3 DualShock, if that's all you've got.)
Take a look at someone else's play-through of Extraction's first level on the Wii, if you'd like to see a comparison.
I don't know if EA will offer Extraction as a standalone download for PS3, nor whether they'll ever release it for the Xbox 360. But if you are at all considering the game, I encourage you to read my Wii Dead Space Extraction review. Dead Space Extraction is a superb light-gun shooter.
The recently-revealed upcoming expansion to Dead Space 2, Severed, will be an extension to Extraction.
(By the way, I hear Dead Space 2 is pretty good too.)