Vantaggi
They pay a decent paycheck and you can get experience in game development which you might later be able to leverage to get a position with a real game developer.
Svantaggi
They're a huge faceless publicly traded money-hungry company that cares nothing about the quality of their games except insomuch as it can drive sales. Their executive leadership knows too little about the realities of game development (at least historically), and the culture at the executive headquarters is unbelievably political and competitive. They pit the different internal projects against each other, forcing them to create throw-away work to make the game look more complete than it is, for a quarterly dog-and-pony show to the executives - and if your game looks less impressive than the other internal products, it might get canceled!