Isaac Asimov, Sir Arthur C. Clarke and Robert A. Heinlein; I have an ambiguous relationship with the Big Three of science fiction. As a boy, they were among my favourite authors; right up there with Sapper and H. Rider Haggard. But when I started work on Tales of Future Past I had to reread their stories again and I found myself confronted by a very uncomfortable fact: however enjoyable they were to read, their writing was dreadful. Asimov's prose was schoolboy stuff locked in an adolescent sense of language and a complete inability to describe anything, Clarke's was dry and passionless for anything that wasn't made of duralloy with rockets strapped to its sides, and Heinlein's read like a good writer of juvenile fiction who aspired to creating bad pastiches of Kipling–which he was.
I'm rereading Heinlein's Starship Troopers at the moment and for all its powersuits and other toys, it comes across as if Heinlein had read All Quiet on the Western Front and figured that the best reply was a short novel so plotless and so sanitised that it reads like the script for a US Marines recruiting film circa 1942. It's either the worst of Heinlein's juvenile novels or the best of his later adult novels, which isn't saying much because Heinlein was poised for the deepest and most-drawn out swan dive in literary history culminating in the unreadable nadir of The Number of the Beast. I have a particular hatred for that one because I was on a hiking trip in Germany back in the '80s, I was tired of reading everything in German, and that was the only book in English that I could find.
God, it was bad.
That said, Heinlein was still a fascinating author who defined science fiction for over a generation, smashed that definition with his Stranger in a Strange Land, and then got all cross when people stopped taking him seriously. He's was also a much more complicated writer than many people give him credit for and a study of his work is well-worth the effort as a way of learning how to write and (more important) how not to write.
The best work I've found on Heinlein is Alexei Panshin's Heinlein in Dimension, which looks at Heinlein's writings from the beginning through the late 1960s. pulling no punches, Panshin not only examines Heinlein the author, but also explains his peculiar world view that could almost be called two-fisted solipsism. If you've ever wondered why all of Heinlein's secondary characters are so thin as to be non-existent, here is the answer. And if you think that his main characters sound like a man talking to himself, there's a very good reason; he is.
If you have a free couple of hours, I recommend that you peruse Mr Panshin's book. It's both highly readable and available free online.
Update: More on Heinlein over at Ephemeral Isle.