While I don't like auto aiming, I don't think that its gonna be game breaking. I never found any of the metroid games relatively difficult so having auto aim won't make it much easier for me. I just feel that it will make the game flow faster as you can just go through a narrow corridor shooting and not having to worry about if you hit them or not. I would rather have other M be a completely 2d game similar to the way retro studios is handling DKC:R. 2d game with great looking backgrounds would've been ideal IMO. Still can't wait.
Edit: Also, I'm not liking this "tacked on" story that they're putting in Other M. One thing I liked about past Metroid games was how alone it made you feel (kinda like Dead Space but even more so) and Samus talking is a big no no for me. Also, that you are notified of a secret item in the room you are in takes away from the exploration of past Metroid games. Before, you can beat the game plenty of times and miss an energy tank or two because you didn't know it was in that room. Minor gripes, I guess it's because I'm an old school Metroid fan.
