7.5 Stars. Entertaining but not a Best Picture IMHO.

Rating: 7/10 (18 January 2016)

I'll give it 7.5 stars. It's a good movie, entertaining, but I don't feel it's an Oscar-worthy "Best Picture" film like the vote-pursuing advertisements have been saying.
Damon does a very good job. The flaws in his performance are not really him; they are to be found in the writing. I saw the author (or was it the screen-writer) recently on TV, saying that he does indeed see people as having this kind of pervasive positive attitude. Personally, I want to live where he lives, as remaining 100% positive, like Mark Watney does, for so long seems to me to be very unrealistic. Still, suspension-of-disbelief is necessary in movie watching... and this is no exception here.
Recently, I believe, this film won 2015 Best Comedy on the Critics Choice Awards. Ridley Scott responded with his non-understanding question "A Comedy?" and he was the director. The humour is used to maintain the positive attitude of the stranded Watney. It appears that is has been misunderstood as the theme of the movie by many.
There are equally misunderstood leaps of logic and achievement (by the Watney character) in the film. So prepare yourself for a good film, not a great one. Be entertained and hope... hope that we have more people who could indeed be so uplifting, so positive, and so intelligent, as the Watney character is, in real life.