That's interesting. I rarely abandon a film once I've started. It has to be truly atrocious to the point of annoying before I'll give up. For example if I find out 20 minutes in that Ben Stiller is in it. That might do the trick. I guess if I'd gone to see it at the cinema I'd have stuck it out, but this was a rental DVD, and I just couldn't be arsed with it.
I'm a big fan of Chris Nolan and have tried twice (Cinema and BluRay) to get into Inception. Still think it's one of his poorest movies.
It's also nowhere near as clever as people say it is or the writer would like you to believe it is.