I was kind of curious if they would make this game into something interesting, and they could have easily done that. They could have essentially had you play as the Metroid Universe equivalent of Star Wars clonetrooper special forces squads going around the galaxy fighting space pirates and aggressive wildlife. You'd rescue survivors, protect colonies, do scouting missions, etc. Maybe it played like Xcom, or Valkyria Chronicals. Maybe it played like Resistance or Halo. Hell it could have been Metroid:Battlefront and let you play as literally every Metroid character or monster in the series as well as introduce new ones.
It could have been THE flagship FPS for people not into Splatoon on the Wii U and while not a traditional Metroid game it could have been really fun as long as the gamepad screen was used in a good way instead of like in the new Star Fox. Hell even the football mini game could have been an alternative to Rocket League on consoles.
Instead they made this, on the 3DS. While I can't say I've played it, I can see that the prevailing assessment is less than positive.
Personally I'm happy with the GOOD games we already have. My favorites are Zero Mission, Super, Prime 1, and Prime 2.
I like Fusion, but given that it kind of painted the narrative into what has become a dead end, and that it led to the abOMination that makes the good ones non-canon I think I can safely leave it out of the top tier.
The other games are all good, except Hunters which I don't remember much of but do remember it having terrible controls and graphics.
These days games like Song of the Deep, Oceanhorn, Xeodrifter, Steamworld Dig, Fairune, and Axiom Verge take the place of equivalent Nintendo franchise installments as I think the last game of theirs I got was a Link Between Worlds and before that it was probably Other M.