The Martian works far better as a book than as a movie. It sounds like just another dumb sci-fi book, but it is more than that. It definitely isn't 100% accurate all of the time, but it's far more accurate than the other sci-fi novels I've read. You can tell from the first chapters that a lot of research (or obsession) went into getting scientific and historical details right. This is something that you simply can't appreciate by watching the movie. Reading the book is so different because it's a learning experience as well as an adventure, whereas the movie is just an adventure. But the learning also contributes to the adventure - it IS the adventure in a lot of ways. This is why the cinematic rendition often feels hollow.
A while back I was listening to the Planetary Society podcast, where they were interviewing several NASA directors in charge of the mission to mars. One of the first questions was framed in reference to the Martian, asking if they were planning to build something like an "oxygenator" (a fictional machine). A lot of the follow up questions (and answers) had references to the Martian. It seemed like the NASA directors were actually fans of the book as well, as they obviously were very familiar with terms from the book. That impression alone should tell you that for once, a crazy sci-fi book actually has somewhat respectable science behind it. And where it might lack in very slight errors, it makes up for in spirit - for this is truly a celebration of the scientific method. Except this time the scientific method must be used in a left-for-dead scenario on mars, not a lab.