Vantaggi
Pay is good. If you don't like your job/group, you can move. Although you must network in total secrecy to get something you might want - the official process is a black box.
Svantaggi
After 8+ years of being ranked in the middle and trending upward, my management suddenly dropped me down into the bottom third with absolutely no warning or reason. When I asked why, they gave me bogus excuses that were demonstrably false and they knew it. I have since moved into another assignment, but I am finding that moving up is a helluva lot harder than moving down - your management has to take points from someone else and give them to you. Meantime I'm missing out on raises I would have received if I was only a couple points higher. I may never get back to where I was, even though I have always performed at a high level. Any company where this can happen to a hardworking, customer-focused person is seriously f*cked up.