Pros
So far what I have seen is the commitment to promotion and career development. Comparing it my previous software firm this is something that I have been looking for. Support to move forward and merit wins not tenure. Secondly, from what I have seen Deloitte seems to take this whole process to another level and is very open about it with you. I am sure politics play a huge role with promotions however there is enough open process that you should be able to get a fair shake and not have to work the political side more than actually working. One final note to move up you need to be involved in the sales process if you are given the title of Senior Consultant. That also adds to moving up.
Cons
Learning to navigate Deloitte seems to be a challenge that you needs to work through. It is also the key to getting ahead. The fastest you get this down and your network started the better off you are.