Definently underrated. I came into this game as a fairly experienced Metroid player and didn't really have any problems with navigation, but an in-game map still would have been appreciated. The secrets all feel great to find. The fights with later stages of the Metroids get a little annoying, but I love the way that less creatures are able to survive the closer you get to the Metroid nest, and just love the games themes overall. The game didn't feel too unforgiving either, plenty of save states, I didn't even worry about having to resort to save scumming (played on 3ds). The game hasn't aged perfectly, but I still had a really good time with this one.