It withstands the test of time
Super Metroid is arguably the greatest game ever created. I'm what you would call an old-school gamer but I've played a lot of newer generation games too. Games I've come across over the years that are worth mentioning are Zelda: Ocarina of Time, the original Half-life, Half-life 2, Halo, World of Warcraft, Baldur's Gate 2, GTA3, Vice City, San Andreas, etc. All those games left a lasting impression and they would sometimes make me forget the old school games from my youth.
Once in a great while I would revisit Super Metroid and remember just how incredible the game is. To this day I don't think I've ever quite had the same awesome experience I had the first time I ever played Super Metroid.
I've played all 2D metroid games, including Fusion and Zero Mission. Although those games were excellent they didn't quite add up to Super Metroid as far as gameplay quality, immersion and pure fun factor.
I strongly recommend shelling the 8 bones to get this game on the Wii. Even if you're hung up on the latest and greatest graphics, you should still give Super Metroid a go. You'll discover that a vintage game with vintage graphics will trip your trigger.