There was a bit of a disconnect between what Casey Hudson had to say about Mass Effect 3 and what they were showing on screen when I visited EA's Los Angeles office a while back, but if both pieces come together, Mass Effect 3 will probably turn out just fine.
On the screen, there was an action-focused sequence, showing Shepard fighting against some "indoctrinated" Cerberus agents on the Salarian homeworld. It appeared that he was rolling with Liara and Garrus, but Shepard was definitely doing most of the work and we were shown some faster, better-looking combat. Popping in and out of cover looks snappier, and in general, it all just looks like it's unfolding at a faster pace. You can, of course, still slow things down to unleash biotics and other abilities. Also, Shepard is once again armed with grenades, though they seem more like real grenades instead of the disc-shaped things you could toss in the first game. You'll also have an up-close melee attack, and we saw an updated version of the holographic Omni-Tool that had a fat holographic blade on it. Oh, and it's now called the Omni-Blade. This seems like it'll allow for various kill animations. You'll also be able to pilot large mech suits in some sequences. Much was made of Shepard's "new mobility," and it sounds like he'll be able to more effectively climb over cover, jump, and do the things that most shooter protagonists can do.
This is the point where you're supposed to say "please stop telling me about how Mass Effect 3 is a better shooter, I don't want this game to become a shooter." And that's where the things we weren't shown come in. Despite showing a pretty action-heavy sequence, it sounds like Mass Effect 3 will strike the same balance as its predecessors. The goal isn't to have more shooting. Just better shooting. And the bulk of the game won't necessarily be set on Earth.
Mass Effect 3 opens several months after the conclusion of the previous game, which allows for the cast of Mass Effect 2 to go their own separate ways and give you a fresh starting point for the mission. Early in the game, the Reapers will attack and take control of Earth. Shepard will get away on the Normandy and it sounds like the bulk of the game will deal with traveling around the galaxy and performing missions that help build your war effort as you gain support for a final mission to return to Earth, fight off the Reaper threat once and for all, and save everyone and/or everything.
Mining will not return in Mass Effect 3. I'm not sure how I feel about that. I mean, yeah, mining was kind of a drag, but it eventually became weirdly relaxing. But instead of finding mineral deposits on planets, they made it sound like you'll find actual missions, which sounds like a pretty good trade. You'll command a smaller squad than you found in Mass Effect 2, but the trade-off there is that the interactions with your team are said to be deeper.
The shooting that was shown looked snappier than the action in the previous Mass Effect games, and everything they were saying about the story, the structure, and how it'd unfold had me nodding my head and saying "sure, yeah, I will happily play that game." Hopefully all that stuff crams together nicely and creates a fitting end to the Mass Effect trilogy.