I've now played all three versions of Metroid II, but this was the first of them that I played. AM2R is also the best of these, in my opinion. It encapsulates a lot of the good aspects of the original Metroid II and adds a bunch of new additions to it, such as new power-ups, banging music, and fun boss fights to make it a much better experience overall. It does a great job at surpassing the original in terms of fun and playability.

However, AM2R loses a lot of the things that make Metroid II what it is. The cramped screen and the weird ambient music are two of the things that made Metroid II so unique, and AM2R gets rid of them. Despite this, however, I still consider AM2R to be the definitive version of Metroid II and has warranted five separate playthroughs from me.

If you can find a copy, give it a try! It's both a treat for experienced Metroid fans and people who have never played a Metroidvania before.