I disagree. A lot of Dick's books are bordering on unreadable.
Do Androids Dream of Electric Sheep, The Three Stigmata of Palmer Eldritch & the VALIS trilogy are perfect.
Most of his novels, however, while having wonderful ideas, are scattered and somewhat haphazardly structured.
Almost like he doesn't care about them.
His endings are often poor.
He's a great science fiction writer, sure, but calling him one of the greatest authors of our time is a bit of a stretch.
Not sure if you've read all of his novels, or just the classics. But, there's a lot of repetition within his body of work. And many of his novels are, as I said, bordering on the unreadable. There's always something worthwhile, amidst his semi-coherent drug-fuelled ramblings. That's why they *border* on being unreadable. His ideas are amazing. His novels, more often than not, are relatively disatisfying.
(Note: I'm judging him against all contemporary writers, not just science fiction authors.)