Pros
As the headline suggests, the culture is #1. The staff all support each other greatly, and there is good team cohesion. The staff as a whole is not only knowledgeable about clients and issues, but also about the stresses of scheduling, which is why everybody helps everybody. It's a great place to learn with lots of different environments and systems to support. Any engineer here will learn how to do things the right way, but also see what the drawbacks are of doing something the wrong way.
Kontras
Varied clients with intense demands means that the work can feel neverending. Even if you work after hours for one client, it doesn't mean there won't be another client expecting you to work after hours the next day. Typical MSP drawback, there's almost always something waiting to be fixed.