i just finished the campaign (it is broken into 2 sections). it took about 5 hours roughly. I thought the game was really fun and i can't wait to dive into some multiplayer with my roomies. I think this game is much better than the last battlefront. They lengthened the campaign mode and it actually ties into the story more.
The first section is based on the episode 3 battles, while the second section deals with stuff between 3 and 4 and it was cool to see how things tie in (ie: why the stormtroopers don't talk like the clone troopers). The various vehicles you can use are also fun to use, though i suck at flying in the space battles. The usage of jedi is fun, but i thought it was kind of hard to use them to their full potential. They also don't stay for very long since they don't heal. Another nice touch they added is they made sure to incorporate a couple cool levels from the first battlefront (geonosis, kamino).
Overall, the game is very fun and worth a rental for a get together with your buds. If you are like me and get tired of the shooter multiplayer genre after a couple hours then i would just reccommend renting this game.