Vantaggi
Good for learning how a large company works, and get the hang of corporation stile of work. Also good if you are obedient, and don't strive for more.
Svantaggi
The clients are always right, you re not going to have a winning cause when having problems with them, and the bad feedback resulting from having an argue with them will have your salary stall (it does not matter if the client is a wrong). They just don't care about their employees. The advancements opportunities are null. Technical wise... imagine that if most of the old tech guru's went to different companies for a better salary and advancement opportunities... they have what's left. So don't expect to advance your knowledge after a certain level. I don't recommend them. Only if you are a beginner and don't have any other choice.