I've never gotten into Metroid.
I'm in the same boat as you. I'd never played a Metroid game until Metroid Prime came along on the Gamecube. And that game ruined the experience for me as I just found it too tough. In particular I recall this boss fight (and forgive me, it's been awhile and I'm probably screwing up the details) where you had to fight this giant plant thingy by flipping this mirrors that was giving it sunlight for power. What I soon discovered that while I was on one side of the room flipping a mirror, the boss was flipping back the one you just took care of. How it was possible to beat this boss was beyond me. I never could get past that part and it was the end of my short-lived Metroid career.
I love the Metroid games, well... Metroid, Metroid II: Return of Samus, Super Metroid, Metroid Fusion and Metroid: Zero Mission. The first person aspect just kind of killed it.
I played Metroid Prime on the GameCube and thought it was okay. I used the guide to get all one hundred percent. But, Metroid Prime 2: Echoes just really did nothing for me, and I gave up halfway through. Now, I did see the Metroid Prime Trilogy coming out. Maybe I'll rent it first, see if my feelings have changed about it, that way I'm not out $50.