In 12 the features are pretty similar to 2003, on small addition is it allows you to preview changes before making them, i.e. if you mouse over a different effect in the wordart menu, it will preview your wordart in that effect. It does this for pretty much anything.
The main change is the ribbons layout, no more 2003/97/etc esque layout, its completely different, and is probably going to cause a lot of hassle, as its confusing, and you can't switch back to the old 2003 style layout.