My only complaint with this game so far is from the screenshots I've seen featuring Samus. In my mind or more particularly her armcanon is the issue. It's way too narrow at the nozzle and that makes me wonder how Samus manages to keep both her arm and the guntech in that cramped space all at once. At least Retrostudios Prime trilogy had the armcanon down good.
I can kind of see that. I think her hand might fit a fist's length just before the nozzle, and the nozzle itself can expand for missiles and such like in the old games. However, where those missiles are "stored" is another matter altogether. On that note, though, I always felt that in the 3rd person models, the Prime gun-arm was a bit too long and bulky compared to the detailed illustrations of Metroid 2-3. As you say, it might be more functional that way, but I thought it made the suit just slightly less graceful.
Still, no disrespect to the Prime games, as they've kept Metroid alive and did a heck of a job. Prime 1 is my second favorite game in the whole series after Super, and Prime 3 is probably near third. Prime 2 was interesting, but something about it didn't sit right with me. With all of them, however, I just always wished for a 3rd person view beyond morph ball and screw attack.