For all the people mentioning the reapers, they arent the villain, they are the overall threat.
That was ME2s problem. It had a threat, not a villain. A villain puts an interesting face on the threat (i.e. Saren).
I get the feeling The Illsuive Man and Cerberus are in deep with the reapers. Not necessarily allies, but they maybe got too involved in the whole "use reaper tech against them" and have their own (wrong) ideas about how to stop the Reapers and serve as the main villains, even if they arent working directly for the reapers.
Maybe some kind of "our own worst enemy" crap or something?
Whatever it is, Im hoping its really good. With how utterly shit ME2 was on practically every major story front, I think to make it the narrative waste of time that ME2 was worthwhile is to see everything good about the remainder of the trilogys storyline saved for ME3.
I hope its the longest game of the three by far. If you cant pull out all the stops and make the final act substantially larger and longer, what kind of developer are you?
And again, since ME2 was a long list of box filled shooting galleries (and a few shopping malls serving as cheap, shitty hubs) Im hoping the best of MEs galaxy has been saved for ME3. I wanna go to the asari homeworld with Liara, I wanna see the Salarian homeworld (which I do believe we are doing if Ive heard right - but not just as some war torn shooter combat course).