[DarkHoodness]

@Varrok - I disagree. 3D graphics can work just as well as, if not better than pre-rendered 2D sprites - It depends how well the graphics, riggings and animations are done. Also you'll be adding extra work since every 2D spite would have to be rendered and set out as sequences... For smooth animation you'd have to have tons and tons of sprites. Some of the animation for the original Abe games wasn't entirely smooth for this reason.

As well as what OddHunter said, 2.5D also should also give a lot more freedom for game development. Go and play Little Big Planet (which is the prime example of a decent 2.5 D game) if you want to see how well it can work.

EDIT: Sniped by Glitch. All well he explained it better than me anyway.