Pros
NSerio is a great company where you learn a lot. The team is very technically savvy and you quickly get exposed to international clients. Their business model is very stable so you can either conduct your role here looking to expand to bigger software consulting companies or you can establish a long-term work relationship. I personally spent 3 years but I felt like I could spent 10 or more, such as some of my coworkers actually have. They are family oriented, as an example, NSerio hosts an annual retreat to which you can bring your family along. It's CEO has incredible humanistic ethics and this drives the company culture.
Cons
Not a con really, but at the moment, the company is very boutique in the sense that you shouldn't expect a rapid expansion of going from 50 to 200 people as in other companies or start-ups. So, managerial growth opportunities could be limited by this. Technical growth opportunities though are plentiful and the company supports your constant learning and certification paths.