Pros
As truly transparent company with a reasonably flat hierarchy. They treat their employees very well and enjoy a very low turnover as a result.
Cons
Although it's been making an effort in this regard, XSB isn't the most terribly forward-looking company there is. As a result of its contract-centric development process, most of its goals are rather near-term, and technical debt tends to accumulate, which can be very frustrating.