A big disappointment!
It lacks everything someone would expect from an Metroid game: great soundtrack, perfect controls and a subtle storyline that is told only by the scenario. Super Metroid and the Metroid Prime trilogy were the games that made those qualities the key-points of the series.
In Other M, we have cutscenes to throw the story at the players face. Not only they're unskippable, they are pretty boring too. The plot is pretty lame, and it shows that Samus is a pansy and an idiot. The battle with Ridley only starts after a cutscene where the bounty hunter starts crying in terror. She's also guilty of letting bosses alive and ignoring plotholes.
The soundtrack consists of a few remakes and a bunch of uninspired tunes.
Most times the music is barely noticeable. The sound effects are good, but a few times they get annoying.
The gameplay is not entirely bad, but it has it's problems. Switching between the first person mode and the third person mode is awkward. There's also an command to make Samus go away from attacks and projectiles, which doesn't always work.
Several times, Samus doesn't obey to the player: She's either in a stand-by mode that only allows her to walk, or she's in a cutscene, crying about something. This constant way of taking the control away from the player is an major flaw in this game.
Probably the worst problem is how linear the game is. Doors that show a red light will simply not open, and the player is forced to go throw another way. It's not like the player will open the door, it will open by itself when the plot allows it. That's a constant flaw, that drives the entire game, even after being beaten.
So, in a nutshell, Metroid Other M is nothing compared to other Metroid games. It receives a score of 4 because the graphics are good and finding items is still really fun.