AM2R is quite an achievement. Taking a Game Boy game and fleshing it out, modernizing it, while still staying true to the original in the most important ways, it surely isn't easy.
I'm not going to pretend I played Metroid 2, but from what I've been able to tell, the game is very simple and repetitive, though impressive for its time. It is a full on Metroidvania on the Game Boy afterall.
AM2R is my only experience with Metroid 2 but I can tell how much care and effort was put into it. The game clearly takes inspiration from Zero Mission, which was a fantastic choice. It controls similarly, and the map system is more or less the same. It also gives plenty of options to the player to make the experience more comfortable. If you're playing a newer version of the game there's even extras like a randomizer and Fusion mode, and that's awesome to see.
The biggest issue with the original from what I've been able to tell, is the metroids themselves. Hunting them all down is a chore and a half. AM2R doesn't fix this entirely but it does improve upon it. There are new boss encounters here, many based on enemies from Super and Fusion. Metroids themselves don't change much as you fight them but the environment they're in does. In some situations it can be a challenge to hit their weak spots, and it makes the hunt less repetitive.
And of course, the ending is kept perfectly intact and remains my favorite ending of any Metroid game I've played so far. No spoilers of course, but I'll say Samus Returns's take is laughable in comparison.
I will never not be annoyed that Nintendo took down this gem of a game. Of course it's still easy to find online, but with all the games in the series I've played so far, this is my second favorite, and it's not even official. The devs should be very proud of themselves.

100% completion
gostei: -comparando ao metroid zero mission, gostei mais dos items estarem em sitios menos escondidos e ser mais facil fazer 100%
-o jogo é bonito
-de resto o que eu gostei já se aplicava no zero mission
achei meh: -no metroid zero mission diziam mais ou menos para onde ir, aqui quando acabas uma fase o chão treme (que significa que há uma nova área aberta) mas não dizem bem onde, não afetou a gameplay por isso não está no patamar mau

Fans do what nintendon't. I will readily admit I have a general disinterest in fan games. Most lack polish and, in their attempt to replicate the source, lack any identity of their own, much less the originality that made the original so appealing. AM2R surpasses that expectation by such a margin that it ranks in the top half of my 2D metroid games. Every level of this game breathes life into it that just wasn't possible in the original. Finally, each area feels unique and distinct. Some of the oppressive and alien nature of the original is lost simply by making it a game for normal humans by zooming out the camera and adding color, but that feeling returns in the final zone. However, the highlights of the game, for me, are where it departs from the original and adds its own ideas instead. The bullet hell-esque boss and water area made me forget this was a fan remake rather than a brand new metroid game. In summary, play this game. It's not too hard to find online and far more worth your time than the official metroid 2 remake.

The sheer quality of AM2R is insane. Seriously, this is a fangame, yet they got so many things right! Samus feels amazing to control, the soundtrack fits the atmosphere and they overhauled so many things to modernise Metroid II while still staying true to it.

However, this latter part, staying true to Metroid II is what hindered my enjoyment with AM2R a bit. There aren't any huge places to get lost in, it's usually very clear where you need to go, because AM2R is split up into so many small areas, which makes exploration a lot less satisfying than Super Metroid or Metroid Dread.

Oh and the Metroid fights are also very awkward, which is kind of a bummer if you consider that you fight them over and over again.

Nevertheless, you can truly feel how much love was poured into AM2R and I deeply respect that.

At times it was a bit frustrating, but after getting over the hill around the half mark it really slides through. Considering this is a fan remake it is fantastic.
It is the most accessible way to properly experience Metroid 2 just as Zero mission is the best way to play the first. Kudos to m64 and everyone else who labored for this to be true.

PS: to those who don't know, Nintendo pulled the plug on this project albeit a bit late. The game is complete and is a better experience than Samus returns as many would tell you.

the original metroid 2 was a game about the mindless genocide of an entire planet, piece by piece. everything about it, intentional or otherwise, felt fit to purpose

the environments lack colour and distinguishing features, the metroid fights are messy and repetitive, the music can be just horrifying

it's not a fun game in the traditional sense, but it sells the themes of the game perfectly and the feelings it elicits are unlike any game i've ever played

it's a long, one way descent into the heart of a dying planet that becomes even more lonely and alien the deeper you go, with plenty of time to be left alone with your thoughts

i resent the idea that this or samus returns are replacements for it; there's a lot of games out there like those two, but none quite like metroid 2

AM2R feels reverant and respectful of the original in the sense that the map and structure and all that literal stuff have been lovingly recreated and modernised, but those very abstract, specific qualities metroid 2 has have been lost i think

but that aside, it's a very well designed, polished, professional and fun game that stands alongside the very best of the official games, and if i didn't know any better i'd probably mistake it for one

it understands on a very deep level what makes the later metroid games so fun and satisfying, but maybe not what made metroid 2 satisfying in its own way

basically what i'm trying to say is, they're both awesome, play both! (and maybe samus returns as well idk i haven't played it)

AM2R: Return of Samus is 2D Metroid at its absolute finest. A familiar but beautifully distinct pixelated art style, buttery smooth controls that rival that of Dread's, some of the best music and remixes in the franchise, and perhaps most importantly, a keen understanding of what makes Metroid games - and Metroid II in particular - so special.

AM2R masterfully understands the original's intentions of being a mature, somber story. It has its bombastic moments, but knows how to use them well and sparingly. Its realistically crafted world is filled with mementos of a bygone, highly technologically advanced and civilized era, occasionally littered with the Federation troopers that arrived to try and tame the ancient threat the Chozo once created in the Metroid species. Somehow, it even still manages to feel alive, or at least having once been alive, as its environmental storytelling is some of the best a 2D pixel art game has managed to convey, putting Metroid: Samus Returns' palette-swapped cave hallways to shame.

As the only 2D Metroid game to date to ever include Prime-like logbook entries, AM2R elevates the original's story to new heights while weaving it around - and in the context of - the rest of the saga. This is the definitive way to experience Metroid II, and even a surprisingly good way to get into the franchise as a whole. I should know.

(Disclaimer: most pros and cons listed don’t take comparisons to Metroid Dread into account, because it’s such an inherently differently playing game)

Pros:
+ Best 2D Metroid in the original style
+ Great hybrid combination of realistic, modern lighting and retro graphics
+ Excellent movement and best Shinespark puzzles in the franchise alongside Zero Mission
+ Updates enormously on original Metroid II and is leagues better and more authentic as a remake than Samus Returns
+ Most cohesive worldbuilding and lore out of any 2D Metroid, including grippingly believable logbook entries that add to the already powerful story
+ Unbelievably good music
+ Adds multiple areas absent from the original and official remake
+ Fast travel system and hubworld-like level design is incredibly satisfying to utilize and explore
+ Added connections to almost every game in the series including Fusion and the Prime games
+ Similarly to Super, you can create different kinds of beams by switching them around in the menu
+ Gameplay is simply polished to perfection
+ Still being updated, including support for a launcher and mods!
+ Genuinely almost incomparable in its greatness in relation to previous 2D Metroid titles

Cons:
- Almost the only negatives the game has are strictly caused by the original game’s limitations
• Metroid evolutions can get a bit repetitive, especially at the end when they become more spongey
• Lots of vertical hallways (though they’re thankfully very differentiated)
• Lore explanation for the world progressively opening up is still a bit silly
• Item progression is insanely fast in the beginning and then slows down to an appropriate level, making the pacing feel off (you get ~4 major upgrades in the first area alone)
- Widescreen mode is currently a bit bugged out (will edit out this problem when it inevitably gets patched)

sets a high standard for what fan projects can potentially deliver, controls, exploration, level-design and visuals are all essentially perfect.

the Metroid boss fights suck though, at least the actual non-Metroid battles are a lot of fun.

overall the definitive way to play Metroid II, I still have to try MercurySteam's official Remake in the future.