I was really looking forward to this game. It's a remake of Metroid II, the only game in the series I never got around to play. Apparently I missed out, because the remake turned out to be one of my least favorite Metroid games. Which is not supposed to mean that it's a bad one, as I overally enjoyed my first playthrough - just not enough to feel much like replaying it, and I replayed Metroid Prime Corruption multiple times inspite of it having been my least favorite in the series until Samus Returns. Fundamentally it's a good Metroid game that plays similar to Fusion in that the overall progression is rather linear while individual areas can be explored freely. The maps are well designed, there's a technique that allows the player to grab some items earlier than otherwise possible and there's the usual variety in Samus' arsenal and functions to facilitate lots of explorative possibilities. Boss battles feel too much like puzzles for my taste. They have very clear attack patterns that the player has to go through many and many times because of huge HP pools and the fact that most bosses show up multiple times and have to be beaten over and over.
For a 2.5D game it looks reallly good. The 3D effects work especially well and cause no issues. As good as the graphics are, there's the problem that none of the game's areas really stand out from each other. Considering other games in the franchise you can take glances at screenshots and usually immediately tell which areas are depicted, in Samus Returns there's not much that makes the areas memorable. It's not a huge issue, but considering it's a comparatively long game it makes the experince become a bit stale over time. It doesn't help that the soundtrack is rather weak, too. There's some great tracks, but most of the time all you hear are bland ambient sounds. Apparently they took inspiration from the original which barely plays any tracks, disappointingly so because that's a point the remake could have improved on.
There are two new features that seemed to be generally well received by other players: a free aim function and a melee counter. Personally I feel like these didn't add much to the game. Anytime I stopped to properly aim at something I felt like I was playing an out of place minigame. The counter makes it often feel like a lame mobile game, because it makes combat feel super monotone: most of the time you end up waiting for an enemy charge at you, press the counter button, and then shoot to finish it off. Since there's very little enemy variety that's how most battles in the game go, and it feels more like a repetitive quick time event than a fluid game mechanic. Another big issue steming from this is that most enemies tend to charge into Samus for big damage, that makes avoiding them harder than usual and can make the game unnecessarily frustrating on harder difficulties (and I beat all previous games on their hardest modes). For me the new mechanics broke the game, rather than adding anything to it.
I can only hope the next 2D Metroid will play rather traditionally, otherwise I'm afraid the franchise is truely dead to me because I don't think I want to play another round of this sort of game.