
Metroid Prime is my all time favorite too! It's just so very good. The series as a whole is exceptional. Maybe that's part of the reason for the backlash against Other M. Even though the game is fun to play, the story drags it out of that upper echelon where we expect the series to be. Imagine if they did the same thing to The Legend of Zelda and not only gave Link a stilted voice but also made him agonize over his past in long drawn out monologues.
Anyway, I hope Nintendo gets the ball rolling on a new Metroid soon if they haven't already. It's been 9 years since Zero Mission (the last 2D Metroid) and 3 years since Other M (last 3D) and that's too long in either case.