I saw the movie last night, and it is totally worth the tickets. It may be rated G, but it isn't like other G-rated movies that are so childish.
It begins with a robot whose job is to clean the Earth. He has a pet cockroach as well, and is the only working machine there. He likes old movies, organization, and is a sucker for romance.
I won't say anything else. n.- Spoil the whole movie for ya. Where are the humans? You'll find out... 40 minutes into the movie I think.