In my opinion, the metroid prime series wasn't all that great. I guess I'm just not into fps games either, but I feel that a lot of what I look for in a metroid game was missing / it was too long and required a lot of dicking around.
Anyways, Metroid Other M is not an fps. It's a third person game that allows you to switch into first person to look around and shoot. It's a lot like the 3D zelda games, actually, where the FPS mode is your bow and arrows.
Watch the latest gameplay trailers at
www.metroid-database.com. I, personally, can't wait. This is the first 3D metroid game made by Yoshio Sakamoto, co creator of the Metroid series, and is supposed to stay true to the 2D Metroid games in terms of gameplay.