The problem with Other M was that we had already seen it in Metroid Fusion. Those cutscenes where samus talks about Adam, and his way of referring to her were already told in fusion. The sectors seem to be the same. And there was the one sector holding a secret metroid project that ultimately splits off from the main ship to explode.
With fusion, the wall jumping feature allowed for some additional exploration, while Other M was literally just walking down a corridor to get to the next place.
Other problems with Other M were the first person sections, dodging and reviving being too easy, Samus' voice, Samus having a traumatic experience when facing ridley when she had already fought ridley 6 times before(7 if you count the manga), and the final boss.
