Pros
I've worked at Tom Sawyer for over three years, and one of my favorite things about it is the friendly staff. People are always happy to help and answer questions, and they respect each other as individuals who have personal lives outside of work. The CEO and all of the technical staff are true experts in graph and data visualization as well as software engineering and data science. The products are very powerful as well, and I'm often impressed by the caliber of customers we are able to obtain and the reputation we have built over the years in the domains we support.
Cons
The company is not large, so people sometimes have to do multiple jobs or take on tasks beyond their official roles. I've been able to learn a lot and gain valuable experience this way, but it may not be for everyone.