All that said, Kick Ass was a fantastic movie.
Yeah, okay, so i saw it the other night (in one of those teeny-tiny late run cinemas in town) and really enjoyed. One thing Millar does really well is hit those moments in an action narrative, all that hero's journey stuff, I guess: the Call, denial of the call, trip to the underworld etc etc. When it's connected with strong characters and a sharp execution - as here, and in the Ultimates vols 1&2 and (mostly) in Old Man Wolverine - it's breathtaking. When it doesn't work it feels empty, like he's going through the motions (the current Ultimate Avengers series). When he tries some other story arc - his FF run, eg - he comes adrift.
So, I think he's really good at one thing, and when that one thing works out it's hard to top him. That structural sensibility is not to be sniffed at: plenty of fine writers lack it. Sure, they have other fine qualities (fine prose, eg, or a fantastic imagination) but the structure stuff is what tips a story out and gives it forward momentum. Millars really good at that.