1.) Making the entryway walls somewhat transparent once the door is opened (maybe enable targeting of enemies once triggered, not sure on that one though) and the player is near the entrance would make it easier to at least see what you're walking into. As it stands, you have to walk well into the next room to see enemies that would be clearly visible from a first person vantage point. The player should be able to at least see what the character sees.
2.) Having the character rotate based on the position of the mouse pointer without any other player input directing this (e.g. pressing a certain key/mouse button while moving the mouse) makes using GUIs annoying at best and unusable on an actual mission. While I don't advocate using mouse clicks on a mission *at all*, the option should still be "viable". I'd be shocked if there aren't more than a few mouse clickers out there that would appreciate this. Additionally the current system of rotating the camera and moving feels awkward and not intuitive. Maybe it's just me and maybe I'll feel differently after playing for more than just a few hours, but having to use the middle mouse button/scroll wheel to rotate the camera is annoying as heck (granted I'm still using a Razer Deathadder, but still). I'm not sure how viable it would be to enable remapping camera rotation to say, mouse button 2 when the click isn't on a destructable object/mob and for the same button to fire whatever ability is mapped to it when on a destructable object/mob, but something like that would feel smoother.
3.) Popup tooltips on mouseover for abilities/items on the character/inventory screens so you don't have to click on the stat/item to see things like weapon damage. Some means of easily comparing weapons/gear without clicking back and forth would also be a nice quality of life change.
Having only played a few hours, I'm finding myself really liking what I'm seeing. Can't wait to see what's coming down the line.