Pros
In general they leave you alone to do your work - as long as it is going OK and all is well with the clients. There is more flexibility than with many companies on dealing with life balance issues.
Cons
They hype as this simply awesome place to work but it is just a big smokescreen effort to attract talent. They are much more body shop than they are willing to admit, not a true "consultancy" as they pretend to both clients and candidates for employment. Like all employers, they will throw you under the bus in a heart beat when you are vulnerable and not making them adequate margins, so don't get all into some warm fuzzy delusion that they are any different. The middle management is also very inexperienced and immature in the way they run the business. Not real pros. Understand that you are entering an environment that is on a continuous sales cycle. Delivery of client services is always secondary to scoring the next deal.