Pros
Takes motivated people who aren't quite sure what they want to do in life, and gives them direction and a chance to prove themselves. Really good people to work with. Usually intelligent, motivated and sociable, with the usual exceptions. Promotion system is usually fair, and chances to rise fast through the company come fast. Opportunity to change if you do not like what you are doing. Ability to manage your own career.
Cons
Senior execs emphasis on sales ahead of anything else. Not enough centralized policy on what opportunities to pursue. Snr Execs usually get carte blanche to pursue sales, and can make some very bad decisions that land everyone in it when it comes time to deliver. Inability of many snr execs to say no to clients.