Pros
I worked at Navinet for a little over 5 years. In retrospect, the time spent there has had a positive effect on my career and my approach to work.
I learned from talented engineers on the teams I worked in. I was able to move across teams from development to architecture in the time I was there. Also got an opportunity to work closely with the perf team and interact regularly with the IT team. The company (or at least my group) cared more about getting stuff done than how many hours I spent at my desk. I felt the tech managers who I worked with cared about my well being as an employee, besides worrying about the bottom line and well being of the company.
Sure there was legacy code and customers who do not want changes, but that was part of the challenge at work. Management itself was not averse to change and moving forward. Successful software technology companies often have to with legacy code. In retrospect I learned more working with the legacy stuff, especially the performance aspect, than pushing code out as part of a feature team. Navinet provided me an opportunity to work on problems of scale. At the same time, they had a small-midsize-company-like approach to engineering.
Wishing the best of luck to my friends at Navinet!
Cons
There were some negatives while I worked there, mentioned in older reviews. From the newer reviews and talking to my ex-colleagues, seems like these issues have mostly been sorted out under the new CTO.