I was very disappointed in the book. I enjoyed the film, but I didn't find Joe Simpson to be a particularly strong writer, at least in this book (it has rather put me off reading any of his others). That's not remotely to diminish his experience, but it's not a patch on Jon Krakauer's Into Thin Air IMHO.
I'm exactly the opposite. I thought the film wasn't good but the book captivating. I can't think of any mountaineering friends who haven't read it and understood the tension and desperation and the incredible will to survive it took to get off that mountain, the writing is secondary to the story. Anyone who's ever climbed will find their palms sweaty and their muscles tense as they read his efforts to get out of the crevasse.
Mountaineering literature rarely makes it mainstream. Into Thin Air is not What I would class as the usual mountaineering literature, rather someone writing about an infamous mountaineering disaster. Simpson touches on this kind of guided climbing in one of his later books and the kind of ethos it has created, which in the main runs against the grain of expedition climbing.
Simpson isn't likeable but if you want a view of the kind of selfishness it takes to be a top mountaineer, if a pretty unlucky one, then it's essential reading. His later books are a little mellower but he still has that edge to him which any breathtaking risk taker has, these twitters show he hasn't really lost it.
I'm sure you've probably read Heinrich Harrer, The White Spider and his more controversial 7 Years In Tibet, which most will know from the film with Bradd Pitt.