1. Various combat/gameplay improvements including the smoother cover transitions, more effective powers, wide enemy variety, and greatly improved enemy AI
2. RPG-esque customization options such as the level 4-6 branching power upgrades and the addition of choosing how many guns to carry, which affects how often you can use powers, and therefor can greatly change gameplay between any two players.
3. The dialogue and character interactions, as usual, up until the 2nd half of the earth mission, which inexplicably had none, or close to none.
Specifics that come to mind include Legion just before uploading the reaper code format to the geth, tali drunk, and Garrus's shooting contest.
Loved the game. Easily an 8.5 of 10 at least, for me. 10 being absolutely flawless on my scale, so basically nonexistent.
Still hated the ending. While not enough to make the game suck as some suggest, the ending as an isolated incident is still something worth being upset at the worst and disappointed at best about.
