Just beat the game tonight. I pretty much agree with most of the sentiments in this thread, but wanted to reiterate:
-Combat takes some getting used to, but once you start playing it more like an RPG than a 3PS, it becomes much easier. I also thought it improved greatly towards the end of the game, but that was probably just me getting better.
-Level design is really, really well done. Ilos looks amazing, as do most of the other levels/areas.
-While some of the dialog scenes are hit or miss in terms of graphics, the vast majority are extremely well done. The lip syncing, expressions, and voice acting are simply unrivaled for the most part.
-Finally, the game has an amazing ending! I can't believe how happy I am to say that, as I thought the story dragged for a bit, and was worried it may fall apart in the end. Happy to say that my fears were unfounded, the ending delivers, and then some!
For the sequel:
-Fix the Mako controls. I found them to be too floaty. Just copy the warthog controls guys!
-Tighten up the combat a bit. While it gets the job done, it could be better. I'd even go as far as to say ripping off Gears' shooting mechanics would be A-OK in my book.
-Space out squad finding! I was really annoyed that pretty much every member of the squad was added within the first 2 hours or so, it made each member seem less significant. Maybe a protheon in the squad?
-Let us travel to Earth!
-Obviously, iron out the texture pop-in/framerate issues.
Can't wait till Mass Effect 2!!!