The heroes coming back is what bugged me. They may have been the focus, but they didn't actually win s***. They showed up, bumbled around a bit, took down Osborn in like 3 panels, and then got utterly stomped by the Sentry and the Void. Asgard fell, people died, and the heroes couldn't do anything. Bob Reynolds ultimately killed himself using Thor's lightning, leaving the Asgardians in total disarray and the Avengers patting themselves on the back for nothing in particular. Kind of a terrible anticlimax of an ending for an event that was supposed to be the triumphant return of true heroism in the Marvel universe.
But yeah, it was an enjoyable read up to that. The "short" part was especially nice. After Siege, 8- and 10-part events seem utterly interminable to me. They're even worse when they're terrible, like Fear Itself was.