Pros
Great place to work. If you like a competitive environment that favors the client over the home team, and a management group that runs you 24-7. There are great rewards- if you can claw your way up to Director. Did I mention teamwork? I guess not, because there isn't any. If you have your own set of clients and can start as a Director or higher, then why not join up? Are you a young consultant just out of school? See if you can hack it.
Cons
If you have a family, you can kiss them goodbye. Because you are going to be working, working, working, 24-7. If you're not a mind reader or a butt kisser, look for work elsewhere. If you cannot prove that you are building their business (bringing clients in or making existing clients happy) then you are toast. Just getting the work done is not enough.