There have been many points raised that I agree with, such as the mining being bad (personally I found it to be the single worst thing about ME2). I also think that the combat of ME2 was vastly superior to that of ME1 etc. However as these are points that have already been brought up numerous times I'll move on to something which I haven't seen mentioned yet:
More opportunities to use the full roster of characters in a single mission. Whilst I was playing through the final parts of ME1 I found it bizarre that despite the fact that we were throwing everything we had into the fray, only two of your team could accompany you whilst the others presumably stayed on the Normandy twiddling their thumbs. ME2 handled this much better but still not brilliantly as despite Shepard being the commander, game mechanics still limited him to only 2 squad-members resulting in the unrealistic scenario of a 'deputy' commander actually commanding more people than Shepard! Nevertheless I think it was a step in the right direction and I'd love to see more situations where you can set-up extra squads that pursue their own objectives in parallel to your own (similar to the final mission of ME2).
Personally I'd love it if before a climactic battle in ME3 you could split your team into 3 squads of 3, selecting who goes in which squad as well as which of the 3 is the squad leader and having each of these squads performing different but related objectives in support of each other. In other words what we had at the end of ME2, but more detailed and something occuring at various points throughout the game instead of just at the end (though such events should still be infrequent and certainly you shouldn't use everyone at once until the end).
More opportunities to use the full roster of characters in a single mission. Whilst I was playing through the final parts of ME1 I found it bizarre that despite the fact that we were throwing everything we had into the fray, only two of your team could accompany you whilst the others presumably stayed on the Normandy twiddling their thumbs. ME2 handled this much better but still not brilliantly as despite Shepard being the commander, game mechanics still limited him to only 2 squad-members resulting in the unrealistic scenario of a 'deputy' commander actually commanding more people than Shepard! Nevertheless I think it was a step in the right direction and I'd love to see more situations where you can set-up extra squads that pursue their own objectives in parallel to your own (similar to the final mission of ME2).
Personally I'd love it if before a climactic battle in ME3 you could split your team into 3 squads of 3, selecting who goes in which squad as well as which of the 3 is the squad leader and having each of these squads performing different but related objectives in support of each other. In other words what we had at the end of ME2, but more detailed and something occuring at various points throughout the game instead of just at the end (though such events should still be infrequent and certainly you shouldn't use everyone at once until the end).