I actually just got that game, it's not that hard to find.Side scroller: tight controls(+emergent gameplay), suspenseful claustrophobic visibility, stylistic graphics. Never played the 3d titles.
If anyone's curious someone completed a full scale remake of metroid 2:
The game has been taken down as part of a DMCA request but I'm sure you can still find it online. I also managed to dl a copy beforehand.