The whole Kickstarter is a huge success in general, I agree. It's more money already than I would have thought they will get, and I was one of the positive voices here while almost everyone else thought this will bomb hard. With the last 3 days it should easily reach 3 millions and that's exciting.
I would have liked to see some small things in between, just to "keep the train rolling" and keeping everyone exited by the pure hype factor of "another goal reached" "and another goal reached". Small stuff like maybe a few new heroes to collect, which would be exiting for fans, some other new small unlockables in any other form (haven't played it so I don't know what would fit for this game, costumes? Screen filter? Sound effects?). Maybe just a little making of, behind the scenes, beta scenes, or interview series with a specific stretch goal, simple but also cool. Maybe a special printed manual for the backer versions or for the first print, stuff like this.