Metroid: Other M is by no means a perfect game; first and foremost, the game's plot is mediocre, largely due to the fact that Samus's characterization is, for lack of a better word, shit. I'm alright with the bad voice acting--after playing so many Japanese video games, I'm used to that kind of shit--but I'm not alright with the way Samus acts here and there. For example, toward the end of the game, you'll confront Ridley, who, for no reason whatsoever, causes Samus to freeze in her place and have a complete nervous breakdown. This is, like, what, the seventh (Or is it eighth?) game in the series chronologically; she should be used to kicking Ridley's ass already. In addition to this, a good portion of Samus's dialogue is shitty; it's just so cliche and melodramatic. Fortunately, some of the subplots prove to be pretty interesting later in the game; Ridley's metamorphosis, for example, caught me completely off-guard, and the whole MB storyline was very interesting. Ultimately, I'd argue that the game's plot is composed of good ideas that are presented in shitty ways; great story, bad, bad story-telling.
But yeah, enough about the story-telling. Metroid has never been about story-telling, and honestly, I don't believe this game is about story-telling, either. The game is ten hours long, and less than two of those hours consist of cutscenes or dialogue. The rest consists of good, old-fashioned alien-shooting fun, and that's what I bought it for. First off, the controls are... different, but movement with a D-pad shouldn't take longer than 30 minutes to get used to (And even less for anyone who remembers the good old days where early 3D games used directional pads, as well, for movement). The structure is similar to Metroid Fusion; it's more linear than other Metroid games, true, but that didn't stop me from completing the game with a mere 40% (I'm ready to go back and find all those missed pick-ups). My only real complaint regarding the gameplay is the somewhat clunky transition from third-person to first-person perspective, but aside from that, the game is an all-around fun experience. It's one of those games that you want to rent before buying, though; while it isn't a BAD game in terms of objective quality, it may not provide enough fun to warrant a purchase.
So, in summary, this game has a mediocre plot but fun, fresh and exciting gameplay. It definitely earned that little red mushroom.
1 
Flawed but entertaining *SPOILERS*
Snorlax tits.
And Meowth packing some heat.
What the fuck am I watching.