The very rapid growth has caused some issues. Internal systems and admin are not the best, but management are working on it.
The other issue is that they have taken on some client work that is not to everyone's taste, like testing or project execution without much chance for employees to shape the strategy. Some people like that kind of work, but others (like me) would rather work on making a real difference for the client. Management is open about the challenges -- on one hand Capco has built a fantastic business, growth and consulting model based on long term client commitments, on the other hand they are well aware of the issues it causes some people and are actively trying to fix it.
Things aren't perfect. They aren't at any firm. What I really like about Capco is that management is very open about the challenges and engage employees about the best way to solve them.