It's compelling, Watney is an entertainer and it's his well written sense of humour which makes you keep reading. The novel also moves quickly, essentially only giving us updates when something changes, rather than an in-depth, blow by blow account (though saying that, things change pretty often). The science is in-depth however, you get the lovely impression that Weir set the novel as a puzzle for himself, he relishes fixing unfixable problems and explaining how they were fixed, and why the solution works. This got too in-depth for me at times, a couple of passages went right over my head but I was quite happy to accept what I was being told.
In all it's a brilliant read, my only criticism is that you don't get a sense of the time. Without spoiling anything Mark is on Mars, on his own, for a pretty long time. There isn't really any sense of that time passing, or of the psychological affects or moments of madness that might happen to someone in that time and under that much stress. Watney is written as an american hero, but it might have been a little more interesting if the circumstances had cracked his shell just a little.
I have just started another adventure; Eric Newby's A Short Walk in the Hindu Kush
