Action/Reaction: One of the best additions to ME2 is the paragon/renegade action system. Many times in Mass Effect 2 you are given the option to press either LT or RT to interrupt in a paragon or renegade fashion. The actions range from grabbing a gun out of someones hand, to interrupting someone going on and on, or even blowing up a gas canister surrounding some unfriendly aliens. These actions are quick, show up at unexpectedly and add that extra punch to a cutscene which kept me on my toes, had me accidently (or deliberately) go against the moral side I leaned with most and spiced up things the way quick time events should without over staying their welcome.
Mass Effect (the series) has excellent writing and voice work and 2 upped the ante with good-great camera work, so the fact that Bioware threw in these actions takes the whole experience to an even greater level where even listening to someone speak or watching NPCs argue can throw you in the game at any time.
The non shooting missions: In one mission the player is tasked with attracting a new potential party member through actions in a club. You can talk to people, start fights, resolve quarrels, etc. The one thing you don’t do is pull out your gun in a party of 3 and start shooting up the joint to get to your goal. This mission was great and is one example of several where the role playing totally shuts down the third person shooter aspect and proves that ME2 can stand on its legs on that level alone.
These side missions (I say side, but they really are crucial to the overall game) give the player a much needed break from the regular missions that start and end with nonstop shooting. The game’s spectrum is broadened and the side character personification is fleshed out more (something very key to the “game” aspect). Not all of them are perfect, but these missions could do well to make up more of the games mission types, or at least exist as more optional quests (and not just say paid DLC like Kasumi).
Choices MATTER: Not just as a quest objective here or there, but many things you chose in Mass Effect 1 will carry over to 2 and create a level of familiarity and importance in the universe that doesn’t exist in many games. Also your allegiances can have dire consequences in many situations. Hell the whole end game is choice city where one wrong move can screw up everything. This is a very big leap forward in gaming, and one that is better experienced than reading a few paragraphs about it.