To be honest, I didn't really like it. At first I found it rather fun, and I had sympathy with the characters, but the last three hundred or so pages I found a real chore. And started to find the characters were becoming more distant to me, too. I suspect it would have had much more impact on me if I had read it at the age of, say, 15 or so. The strength of the novel - and indeed the power of it that sees it feted as a classic - lies less in the storytelling as such IMHO, and more in the challenge to conventional wisdom, particularly with regard to sexuality and religion. I can well see how shocking or revolutionary this must have been in 1961, when the book was first published. However, for me now, the idea that, say, multiple sexual relationships is something not only possible but also laudable is not terribly challenging.
And in a way, this is also what I found most interesting about the novel: it is very much a product of its time, in the way that Heinlein's relentless exposition of his own progressive ideas mingles with his own unthinking old-fashioned prejudices.
For example, I found the book to be just as unthinkingly sexist as many other writings of the period. The female characters read to me fairly two-dimensionally. The domestics in the tale, such as they were, all seemed to be women; it is even a woman who comes out with the classic line: Nine times out of ten, if a girl gets raped, it's partly her fault. And while it could be argued that the Man from Mars's love-centric philosophy would allow, on close reading, for tolerance towards homosexual relationships, in practice homosexuality is only referred to explicitly in passing as something to be avoided.
There were other irritations: I found much of the story implausible, even within its own universe. I could not bring myself to be convinced, for example, that a human being, simply by virtue of being raised by Martians, is so totally without any instinctive fear of death that he cannot understand the concept. The notion that the Martians could choose to destroy Earth on a whim was nowhere dealt with to my satisfaction. The Man from Mars's ultimate martyrdom I found irritatingly convenient plot-wise (six hundred pages in? Book fullness is...Must be time for an ending...), and the novel's attitude towards religion I found annoyingly half-in, half-out. I may be a frubbly sort, but I'd far rather share a pint with Jubal down his local than set a single foot inside Mike's nuthouse free-love sect. I reckon I'd run a mile from any one of his converts, terrified by their glassy-eyed euphoria.
Now, I've not read any other books by Heinlein; should I? Is he perhaps simply not my cup of tea? Or would anyone recommend a different title?
I am interested to hear any comments anyone has...