Ok a lot of people have had some choice things to say about this game, even me. Metroid Other M is both a good and bad game. What makes the game good is a whole bunch of things. I'll list them to make life easier instead of waffling on about them but what's good is,
1) It's gameplay is a 3D platformer with simple controls that work better then you'd think, but they could have been better with a controller over the Wiimote or they could of at least allowed nunchuk support.
2)Ninja Gaiden + Metrold = EPIC WIN! It plays like a old Metroid game but Samus's new ability to dodge and perform finishers makes the battles fun and exciting.
3) It looks really good... for a Wii game. I hate using that term but it can't really be helped since the Wii is a Super Gamecube and doesn't have the graphics power of the PS3 or Xbox 360.
4) Retro fun mixed with modern fun.
Now there are some bad things in the game but they aren't really deal breakers but it's gotten the gaming community up in arms and I figured recommend the game now since people have finished their complains but here's a list of what's bad.
1) Story and characterization of Samus. They made her seem very weak and the story would have been better if it was set up as a prequel to Metroid. A lot of people hated the characterization of Samus and to be honest I don't like it much only because of the previous games not actually supporting this characterization they chose.
2) All the upgrade are on you BUT you can't use them until told too. This isn't that bad but it's annoying that you can see all this stuff around you that you should be able to access but you can't until a certain story point.
3) Exploration is limited. Unfortunately you can't explore much during the story and areas get locked off after you leave them and you can't go to them again until you finish the game and play the extra scenario for the true ending.
I originally gave the game a 3/5 and I stand by it still today. I am mainly recommending it because the game is good and if more people buy it then the next Metroid will be the same style but hopefully back to the original formula. Do we really need another Metroid Prime style Metroid game yet? I say the next FPS Metroid should be held back until the HD Nintendo Console comes out.
As for the game not selling to well it's mainly due to the female fan base as well as people who've played the original not liking the characterization of Samus... That's it.