Avantages
ISA's environment is different from your typical consulting environment, and based on my experience, in a very good way. The company sells itself via the quality and experience of the people you work with, access to and opportunities to learn from highly-skilled executives, as well as a supportive and collaborative environment in which professional development can be individualized and accelerated. I cannot imagine having started my career at any other consulting firm--at ISA you do have the same type of workload you have at any other firm, but the people and the environment make you actually want to work and stay late at the office. In summary--a great place to work, learn, grow and enjoy the work you do.
Inconvénients
Like any other small consulting firm, ISA lacks some of the infrastructural resources you might find at large firms.