Menacing or cuddly, depending on how you look at him. Kirby's nemesis and the first on Brawl's pro-gaming tier list, Meta Knight will be appearing for the second time in Smash Bros.
He's going to behave a bit differently according to series creator Masahiro Sakurai, who wrote:
Meta Knight's Up Special Move, Shuttle Loop, changed quite a bit in this game. The glide is gone, and the attack slashes opponents twice while spinning in a large loop. This has turned into a highly technical and effective move.
Let's take a look at a few screenshots:
Meta Knight [Official Japanese Smash Bros. Site]