The plot seems a wee bit too familiar to the plot of the first movie (super heroes using their powers again even though the government doesn't want them to; a possible villain wants to get one of the parents back into fighting crime; the kids want in on it; etc.)
But then again, who knows if Brad Bird has some new plot twist added in. I'm pretty sure that I'll enjoy this long-awaited movie either way. 
I do appreciate how the plot still involves real-life family dynamic, and that they didn't forget the ol' Underminer!