Aside from a Metroid fan's hopes for the future, I do wish the game was less linear. It's a great game, but I think they tried too hard to be the next Halo rather than sticking with the Metroid formula. While some people may hate it, I love back tracking. I don't see what's so boring about it. Back tracking is part of what made Metroid interesting in the first place. Super Metroid without the backtracking wouldn't have been anything near the masterpiece we have.
Actually, "linearity" is an issue a lot of Metroid games seem to be having. Metroid Fusion and Zero Mission all basically told you where to go. And all of the Metroid Prime games have done the same thing. Since the series was revived, we have yet to get a Metroid game without something telling us where to go. Meanwhile, Castlevania has stolen the Super Metroid formula and keeps churning out masterpiece after masterpiece.
So, yes, good game, but still not better than Super Metroid.
Now on that I definately agree(not that I wasn't agreeing, just moreso on this). Fusion and Zero Mission pushed it, even Prime 1 did it a little too much, but MP3 is far too linear for a Metroid game(it still qualifies, but only just barely).
And while I 'like' backtracking, I more or less like what I call 'strategic backtracking', in other words, looking up your map(or mentally glancing at it for earlier games) and sort of noting where you were that might benefit from the power you just got, or where the next boss might be, etc, and then finding either the fastest route possible, or one that had powerups that you missed.
The Prime series got progressively worse on that note. In Prime 1 you were more or less able to find an alternate route to backtrack on, especially if you just picked up a power that allowed you to go a direction you couldn't before to shortcut on. Prime 2 more or less just had a FEW connecting points to the stupid 'big three' areas, and Prime 3 was ALMOST an all-out 'turn-on-your-heel and go RIGHT back the way you came' sort of backtracking.
And MP3's level progression was no where near as subtle. If you couldn't go somewhere, not only was it a loss of time between loading screens to get there and suddenly realize you couldn't do anything, it was ALSO a matter of an obvious roadblock. You're forced(with reason) onto Norion, you can't enter Elysia without having beat Bryyo, and you can't even access Valhalla, "Homeworld" or Phaaze without doing an event to add them to your map. In other Metroid games, it's usually some sort of land-feature that looks natural, but coming back you suddenly realize 'hey...that natural-looking design is actually set up just right for 'this powerup' to work on it'.....I wanted more of that, more "ohhhhhhhh, I should use THIS on THAT!" sort of moments.
Ahh well. It's still a great game, if only because the presentation makes up for that lack of Metroid-esque stuff. The space-jump/screw-attack differences don't bother me too much, I kind of expect it to be difficult to program into a 3D control scheme this early anyway, but ahh well..