Probably the best thing about the movie is that it doesn't take itself seriously. There's no attempt to make this an epic movie. It just brings the game's characters to life. They do so while keeping the art style in line with what you see in the game. The story of the very simple game is expanded without adding too much like how everything works. The game's story is simple and this one is too. Fear not, there's a lot of room for sequels.
Go in expecting nothing, otherwise you'll be disappointed. It's a good film to turn off your brain to and just let the light drizzle onto your eyeballs.