Vantaggi
I cannot think of any pros, though they have some very good people with solid consulting experiences who used to work for big fives. You can learn quite a bit from those selected individuals though it is pretty much depends where you are in the organisation and what you do. If you work with any of those partners or associate partners then you can learn quite a bit and they are usually very good at couching. Though you have to be very lucky, to me that happened once in seven years.
Svantaggi
I really don't know where to start, there are little career opportunities and majority of people in there didn't have any career progression in last few years. The consulting business is very small; you might hear some big name customers though Atos exposure is very small. You might hear that they are competing with Accenture, PwC and others but in reality they usually get work that big consulting are either not interested or the work doesn't have any strategic significance. Most of the time you are competing with never heard other consulting organisations. Their compensations are not comparable with other larger consulting organisation, like for like you can earn at least 30% more outside of Atos. There are no career opportunities and getting promotions are so difficult, once you get a promotion, pay increases are very small 1%, 2% or 5%. Training is a non-existence; in my 7-year tenure, I had one.