So after having both read the book and watched the movie...I think it's a tie for which is the superior version. The movie cut my two favorite sequences--and my favorite joke--out, but it also has a far better denoument and some really amazing cinematography. Consume whichever version you feel inclined to.
There's no getting around it; Weir is not a great character author. The characters do their jobs, but I wouldn't call any of them deep or moving. It's a lot like vintage hard SF, with the focus on the science and not the people. The most touching moment in the whole movie was the note Watney left in the rover, which was, of course, added.
Speaking of the science, The Martian is only *mostly* scientifically accurate. As others have pointed out, dust storms aren't actually that powerful, and radiation is handwaved with unspoken unobtanium hab canvas. Nothing I'm unwilling to forgive--radiation is a huge problem that you pretty much have to solve with handwavium--but something worth noting for the purists (like my dad).
Is this even a book? I read it in a day and a half, which is less than it took for me to read I Am Legend. The wordcount is probably barely 50,000 if that. More to the point, there's a fair bit of filler content at NASA. It leaves me with the impression this was a novella an editor wanted expanded or a NaNoWriMo challenge.
The ending climax for the book has the rest of Watnety's crew being all badass and amazing. I'm seriously disappointed that with *these people* the author decided to opt for Robinson Crusoe rather than finding a way to strand the whole team. Seriously. Drop the whole team on Mars and let them bloody colonize the place permanently.
It might be just me, but I'm getting STRONG Mission to Mars vibes. Like Weir watched it, took the marooned on Mars plot element, and turned that into a story. I know in my head Mission to Mars is a terrible movie, but I confess I have a soft spot for it.
Freeze-dried potatoes by sticking them in the airlock. BRILLIANT! FINALLY SOMEONE GETS SPACE!
Sean Bean didn't die. He resigned. Funny how the movie bucks the letter of the trend while keeping it's spirit. At this point I'm sure Bean is in on the joke.