Pros
You get a lot of exposure to the security industry and you can learn how a large company makes money. You have the potential of a lot of resources behind you and you have a very big name with a long history.
Cons
The organization is too big and distributed. Too many layers of management. Disorganized. Way, way too much contention between sales and installation. Installation doesn't really care what the sales person agreed with the customer .. they just figure they will do it their own way and that it will be good enough. It usually isn't. Everything is a fire becuase no one pays attention, so everything get done half-ass, and then we owe the customer so we end up doing more than we would have in the first place for less money. It's an endless cycle and not good.