The movie tells a story about the 120 year long journey of spaceship Avalon. Carrying 5000 hibernated passangers towards their new colony world somewhere far.
Right at the beginning of the movie something goes wrong and our protagonist Jim is woken up 90 years too early. He tries to figure out whats wrong, explores the ship and finally almost gives up to loneliness. He is then 'saved' by the girl.
The movie isn't scifi. It tries to be comedy, a love story and there is elements of the catastrophe movie. Some of the ships computers replies are hilariously unintentionally sarcastic. It tries to be too many things without succeeding in any of them. At best it's at the castaway genre. A Robinson Crusoe adaptation where the man gets stranded but this time before the shipwreck.
The story doesn't leave much of whys. Other things however do. Like why does it take laser communications signal 19 years to reach back earth if they have been traveling 30 years with currently 50% speed of light. Even if they could have jumped directly to that speed they shouldn't be more than 15 lightyears away.
So it's probably better switch of your brains and just enjoy the view. And what a view. It's visually stunning movie with beautiful views of space. Also the ship itself is of interesting design. Borrowing lots of cues from classic scifi like 2001, Star Trek and Alien.