Maybe this is a sacrilegious comparison to make, but it reminds me a little bit of a video game, in that it has co-op and competitive modes.
Excellent post, you pretty much summed up my reasons for purchasing IA.
I'm the "enlightened" one in my gaming group (the one who introduced the world of board/miniatures games that weren't Clue and Monopoly) and Imperial Assault is a perfect example of a game that captures that video game like addiction in a box: great looking models, grounded gameplay mechanics, map exploration, exciting scripted events, expansive player upgrades and a neat little story attached to the whole thing.
I just can't wait to show it off with my group!