This game is shockingly faithful to the original. Zero Mission took a lot more liberties in its remake, probably since the original Metroid aged much worse than II, but I played a TON of Metroid II back in the day and this is nearly identical in layout. Obviously the items are different, Charge is where Ice used to be, Speed Booster, Supers were added, etc., but it did a really nice job bringing back in the old. The new stuff might be my favorite, though, like the new Torizo boss and the logs.
It's a little too bad that the music is all remixes of Metroid tunes, like Brinatar in Area 2, Great Temple in Area 3, and Chykka for Torizo, but they are good remixes, and way better than the OG's bleeps and bloops!
Best part is that it's in color now. I always thought the big pillars at the bottom of Area 3 were pipes, but I guess they're thick vines! Makes more sense that way. I just made it to Area 4 (with the Zetas). This is certainly way better than anything Nintendo's done for Metroid in the 2010s.