Vantaggi
I worked with some outstanding people and had a few great managers. Being a consulting company, you may or may not get to work on a project/contract that matches your interests and career goals. There are plenty of opportunities for growth if you are able to actively network and promote yourself.
Svantaggi
There is a huge difference in culture between the "elite few" who work in the corporate HQ and the front-line grunts working day to day on client sites. If you're full-time on a client site, you probably will be ignored by management except for a few perfunctory all-hands meetings where they talk about revenue and margins and other things meaningful to them and meaningless to you. This is a contracting company, so you are only valuable as long as you are billable. The company says it values its employees, who are after all its only asset of any value, but training and professional development is expected to be done in your "plus 40" time, and preferably without costing the company anything. There are some good managers who will push to get around this policy for their staff, but others aren't motivated to push through this to develop their people.