Pros
Grid Dynamics was a FANTASTIC place to work. They essentially function as a resource management company where you will be contracted out to their customer for different projects. It allows for a wide variety of different opportunities.
Kontras
The only downside of Grid Dynamics is that you are tied to the viability of the different contracts. While Grid makes every effort to keep you with the company between contracts, if there aren't any contracts with openings then you will be released. However, Grid has a concept of putting people on a "bench" where you get paid while you wait for a new role in a contract.