The more he writes, the more I'm convinced that OSC just got lucky with Ender's Game and Speaker for the Dead. I tried to read Xenocide about four different times and I'm convinced it's unreadable. I also read some of the Shadow books and I thought they were painfully average.
And yeah, he's a dick.
A lot of what people have listed here is actually pretty good stuff (not Fifty Shades though, ugh) but yeah, I can see why people would have trouble getting through it. It took me three attempts to get through Gravity's Rainbow but it became one of my favourite books.