I guess the best way to describe Other M would be "disappointing." Judging from screenshots of the game you would assume that this was simply a return to the 2-D side-scrolling roots of the franchise. That would have been a good thing. Instead, this is a weird third-person/first-person hybrid game that has you constantly flipping the Wiimote around to change views. This is not quite as awful as it sounds, but the game would be much better if they had just chosen to go one way or the other. As it stands, the 2-D sections of the game, which could have emphasized platforming and twitch skills, are dumbed down to "press right and hit fire... the auto-aim will do the rest." The 3-D parts are equally disappointing. Unlike the Prime series, exploration and investigation don't really play a role here. The first-person perspective is mostly used to charge up your super-missiles and lock on to targets.
On top of the awkward game mechanics is an equally awkward storyline. This is the first time the the Metroid series has been given a largely dialogue driven story with tons of long cut-scenes and voice acting. As bad as it was, I didn't mind this too much. The problem for me was that it was overused. Most of the time a cut-scene would involve Samus sulking and simply restating what the player just saw happen two seconds ago. Rather than advancing the story, she's just brooding like a fourteen year-old goth kid. In fact, I would have preferred if she simply recited some of her bad high school poetry every ten minutes or so.