Pros
Some of the best reasons include: generally very smart and curious people working with you, generally very sharp and capable management team. Clear career path(s) and opportunities to change your path. Generally good support from leadership and a process to manage nearly every situation. Good place to learn structure, approaches, rigor. Big plus is their nonprofit program: Accenture Development Partnerships. It's a unique and very real contribution to the world outside of just working for profit.
Cons
Cons include: uninteresting work, truly one path for significant rewards and recognition, inflexibility on travel, payscale too low. Typical to want 150% from people and not give you any room for having a life of your own outside of the company. The rewards and recognition system only works for people who want to sell, run large programs, spend spare time working on Accenture community programs, etc. If you have expertise in an area and help Accenture buy working on small projects that are revenue generating but not "huge" then you aren't bound to go up in the company.