Metroid was right behind Zelda on my list of NES favorites. The graphics and memorable music gave it an atmosphere that was unheard of in console games at the time.
It's a bit rough to play these days, because Super Metroid (heck, even Metroid II) improved so greatly on the mechanics. I primarily play it as the unlockable in Metroid: Zero Mission. Ridley was also super-easy to beat in Metroid with just the Wave Beam, while Kraid was much harder.
On the Samus gender thing: My totally-in-denial best friend when I was that age argued that Samus was a male rock star like Keith Richards, I argued that she was female.
Fun fact: "Samus" is the feminine form of the common Irish name "Seamus". That would have settled the argument right there if Seamus/Samus were common names for Americans ("Seamus" is the Celtic version of "James"), but that was lost on us.
