Sales have told the story, unfortunately, though doubtlessly more factors are in play than this being a subpar Metroid game (lower sales in general for second iterations of anything on Wii, higher piracy and a general stigma against core Wii games that was not present when Prime 3 launched)
clearly it's an under-performer for the franchise, even if i still say it'll slide past a million, it'll be down with Metroid Prime 2 (which in my subjective opinion was a worse game than this by a decent stretch)
As for myself, no. As i said long ago, I generally approved of this Samus because this Samus did not really clash with my image of Samus as someone introspective and reflective, generally aware of the gravity and generally tragic circumstances she's caught in.
Some of the plot elements were downright bizarre. The whole Other M/MB/Madeline Bergman thing was a nice twist, but wasn't introduced well enough. They should have hinted more strongly that there was one central driving force behind the breakdowns on the ship
My only other gripe was that in terms of setting and very general plot, this was basically Metroid Fusion Redux, but we really can't blame anyone for that idea, given that the extremely treasured Super Metroid is pretty much Metroid Redux, and even Metroid Prime is Super Metroid Redux. As far as setting goes, Metroid's been at its best retreading old ground before
As far as gameplay itself? Mostly golden. I'd nix the Concentration and return to pickups in the future, but absolutely keep the general style, a silky smooth blend of 2D and 3D that really captures the agile Samus of the 2D games in a way far surpassing the tanky Samus of Prime (and i still think Prime's the best game of all time, so don't attack me on that point)
All in all, it's still a worthy entry in the franchise, but lacking in the refinement and polish that has been another staple of previous Metroid games. The story could have really clicked perfectly if they had ironed out a few of the finer points. Delivery was too heavy-handed, but the general portrayals were all great, some of the finer gameplay mechanics needed to be fixed as well
EDIT: Really the also kind of dropped the whole "Deleter" thing into the void. Obviously the man killed by MB was the deleter (since you saw her being attacked by the Deleter, but she lives and in her lab this corpse is found), but for a game that tended to shove finer plot points in your face, they left that one for you to figure out on your own