Saw it two days ago. Aside from Matt Damon being (Surprise!) a miss (oh, Chastain too), I thought they managed to remove all of the charm that made the book so oddly brilliant. Costume design is all-around excellent, though (with the massive exception, I thought, of the NASA staff) - cool to see Janty Yates doing something that looks so relatively normal.
Funny thing about Ridley Scott - I thought the cinematagraphy could have been, shot for shot, prometheus. It's really right up his alley - claustrophobic with interspersed epic panoramas, lots of profiles and closeups, quiet tension. I mean, you replace Watney's McGuivering with some space aliens, and you have yourself a Prometheus 2.
Anyway, people are calling it the greatest SF movie all time, which is ridiculous (I'd say that another well-known Ridley Scott movie is a pretty good contender, though). Don't listen to the hype and maybe you'll like it OK.