Great ending Yes, I agree with others that there are definitely some questionable decisions made by the crew on more than one occasion. Putting that to one side, the movie is well worth a watch if you like science fiction. I've watched it twice now. With similarities to Alien and other movies, it's not entirely original, but, heck, what an ending.
I liked most of the actors, especially Jake Gyllenhaal, and the spaceship interiors were suitably claustrophobic. There was a good amount of suspense, which had me needing to resist the urge to fast forward to escape the tension.
For me, it's a solid seven out of ten. Well above average.