Along with Volvagia, Gyorg was one of those atmospheric bosses that really stuck with me upon playing the 64 generation of Zelda games. While Volvagia was this entrancing and living fireworks display/game of whack-a-dragon, Gyorg was pretty much the Zelda equivlent of Jaws. What's worse is you had to SWIM with him in order to beat him and it was immensely unnerving having to actually go into the tank with him. Thus, I think Gyorg is probably thee most intimidating aquatic monster Link has ever faced.
He does seem to be one of those bosses that really draw you in and make you remember him, even if that remembrance is one of loathing. His fight seems to be fairly nerve-wracking, and I hope I get the same feeling from him when I eventually get around to playing MM, since I finally got it on VC.