Pros
A young and highly technological company, where you can work for a lifetime, having the opportunity to learn every day with the big client companies you can work with. The high professionalism that they push you to have, from the first day, has generated a speech within the employees which is that if you start in AYES, you will be an AYES forever (respecting the high level standards you want to keep). Very often salaries and benefits are better than large companies. The big difference with other consulting firms is that management is really done as a team. All managers have already been consultants and understand you perfectly in the situations you can foresee. In addition, there is usually reliable communication, where you can speak frankly, ask and make suggestions. I have worked in several consultancy firms and frankly, this is the first time I have seen this approach. You don't have great directors who come with big cars, play with their secretaries and go home early, you don't have bad political things ... it's a really positive and reliable place to work.
Cons
Workload may vary significantly from one project to another; however project with heaviest workload are often the most innovative ones where you can learn a lot.