In my opinion San Andreas is an enigma. Now I don't mean by any definition that this movie was intelligent or thought provoking, but in the sense that the movie doesn't know what genre it wants to be. It jumps between being a character driven movie about a father and his daughter to being a Michael Bay-esque disaster porn movie. However that is not to say that the characters are badly portrayed in any way, it just feels like at times their needs get in the way of the main story.
As is the standard for most disaster movies the main characters should have died in every other scene, but as The Rock would say "It doesn't matter!". One thing did really annoy me about this is Carla Gugino's as Emma, who's clunky acting made her story entirely un-engaging. This sadly was not helped by how her character was written, it seems her motives and goals change every time the city shakes.
However the CGI and action manages to redeem the movie to some extent, making it one giant strange mess that still manages to please the audience. If you have two hours spare and need to give your brain a rest this is the perfect movie for you. I would give it in total a 5/10, it certainly isn't going to win Best Film but is a fun disaster romp nonetheless.