Pros
They recruit heavily out of colleges and have a very young talent base. Many projects are setup to take many fresh college grads each year. They do a good job of mentoring and assimilating people into the workforce. The work/life balance is good and once you've been working there a few years you often have opportunities that most people in that experience range wouldn't, such as managing others (often new college hires). From my experience annual raises were above average.
Cons
You're often at their disposal in terms of assignments and work locations. In the first few years many people change projects. A con of having younger leads/managers is often people who have no idea how to effectively manage get placed in those positions. The company's structure is very flat and vague. You start as a Consultant and then don't see a title change to Sr. Consultant until the 5 year mark. This can make it hard to tell 'where you're at' career wise.