Pros
Portland Internetworks is by far THE greatest job I've ever had. The culture from the bottom to the top is a fun and welcoming environment - whether it's a tough problem that we team up to knock out, or the grueling ping pong tournament as we fight for the yearly trophy. I'm primarily on the technical side, and I can honestly say that I wouldn't be half the engineer I am today if it wasn't for working at Portland Internetworks. We are a growing MSP and the opportunities to rapidly learn new technologies has helped my personal and professional growth more than any self studying could. Those are opportunities that I wouldn't get working in a corporate job where the environment is so static I don't have the chance to branch out. The people are great, the job is constantly throwing new challenges our way, and Portland Internetworks is a great place to work!
Cons
The only cons I can think of would be the normal "Small Business" issues that everyone fights. We often wear many hats and have different responsibilities due to the small size of the company. There are jobs that need to be done that simply don't warrant a full time employee. On the technical side, we do an on-call rotation where we are available 24/7 which can eat into a weekend if something happens. It is pretty rare to get those emergency calls, but when they happen it can be long hours to get things back up and running.