I played the original Metroid, but wasn't terribly fond of it. I did have a lot more fun with it when I had a Nintendo Power set of maps.
However, Super Metroid was the game that hooked me. I first played it when we rented it from our local rental place, and couldn't put it down all weekend. Of course I wasn't able to complete the game, but it was just so much darn fun. My brother got pretty ticked at me for not sharing.
I think the item I enjoyed the most the that dash boots. I loved being able to speed up to get invincibility to plow through enemies. The item that I got stuck on before having to return the game was the Gravity Suit. I just couldn't find it, so I couldn't advance to the wrecked ship, because of the water.