No new gameplay features were seen, except for the new blade featured in your Omni-tool. It is a dagger that forms from your arm. Finally a way to help in close-combat situations. Laser sights and leaning around corners.
As for new characters only one was present; a girl Krogan kept in a chamber, at least that's what it looked like. An array of familiar characters were seen though, like Garrus, Legion, Joker, and Mordin (if you kept them alive that is).
Mass Effect 3 was announced to feature Kinect Capability. Is this a good thing? It will involve you choosing your speech options and leading your team. You can tell your crew members where to go and what powers to use. It seems pretty decent, but overall laggy. Hopefully it was just the stage demo. Also, why can't you just use your headset? Just a way to get people to dust off that Kinect I suppose.
Mass Effect's release date is also set for March 3rd, 2012.
Either way Mass Effect 3 is going to be a fantastic experience, kinect or not.