I loved every moment of MP2 as for the backtracking thing I felt it added a nice level of difficulty and I like difficult things (like my gf lol). Seriously though, I thought it was great game, I actually thought it was better than the first one, but only because it built off of it, and added many improvements.
I also like multiplayer Metriod, I really don't know why everything about everything must be complained about. Samus is a solo bounty hunter? Since when do story and multiplayer FPSs go together? (Besides co-op) Oh but Metriod Prime is an FPA! Not when you're playing with other people it isn't. Really how hard is it to detach yourself from a story? I can't imagine the real lives of people who can't seperate fiction from fiction, let alone fiction from life.