I went to see this movie expecting nothing, I didn't even know it existed. We just had free tickets to the movies...
And it was actually great, Eva Green's acting I think deserved an Oscar, and the little girl acts very natural, and you feel for her.
Like other reviewers said, don't expect Sci-fi, it's a very realistic depiction of an astronaut's training, no glamour here, no Hollywood super clean and modern spin on it. Just real looking people working super hard to achieve a great feat.
Tl:Dr Don't expect Sci-fi, it's a very well written family drama during a very realistic and raw depiction of an astronaut training, the acting is great too.