Pros
QVARTZ is a special company with one of the best company cultures I've not only experienced but ever heard of. Clients and projects are high profile and exciting. I think QVARTZ distinguishes itself from American competitors with relatively flat structure -- providing a high level of responsibility and ownership over work from the beginning. Feedback and development are big focus areas and individualized. The New York office is small and growing which gives it a start-up feel and entrepreneurial atmosphere.
Cons
You can expect typical consulting hours most of the time, and travel flexibility is required (both for projects, and for company training and events which tend to take place in Scandinavia). Given that the firm is still around 400+ people, there is not a ton of global opportunity for those who prefer to travel far and wide. The New York office is relatively small, so you have to be willing to go with the flow for projects since there isn't a wide array of industries/functions to choose from.