I went to see it with my sister and her kids yesterday, so, 3 of us were interested in seeing the film before it started. I loved it. My nephew couldn't keep up with it, my niece couldnt get into it because of all the video gamey stuff, and my sister was just bored. All 3 were more entertained by the trailers for Dinner for Schmucks and The Other Guys. I think the problem is while the film is an utter blast for its audience (which I think may of just been me in the screening I saw), and from a review point of view it's pretty much unlike anything else, the average person either can't keep up with how fast paced the film is, is lost by how little is given away development wise by the film, or simply put off by the visual style.
Personally though, I thought it was incredible, easily my film of the year so far, just, sadly, I can see why people who aren't already somewhat invested in it wouldn't like it. Can't wait to see it in HD too.