Pros
You'll work with great people and learn a lot. You will be expected to hold yourself to high standards. The company is large and you can move about/change your role to keep challenging yourself (but when you get into a role, you are expected to stay in it for 1-2 years before moving again). The company is a market leader and the quality of most functions is really high. Despite lots of work and the fast pace, there are enough get togethers/parties/celebrations.
Cons
You need to work smart to keep up with the fast pace; you need to be able to identify what is important and what is not, and drop the not so important stuff -- and be prepared to justify your decision. Most managers will understand if you made a mistake as long as you thought about it rationally first. Your career is in your hands -- most everyone is too busy to do more than give you high-level advice. If you keep your head down and become excellent at your level, you will remain a highly appreciated employee at your level. To be promoted, you need to try and get involved in things that give higher ups a chance to see your work. Salaries are not the highest, though they are not bad either. You could get more elsewhere (but the workplace and colleagues may not be as great as here).