Pros
Some truly interesting tech stack with unique opportunities to learn unavailable at other startups. Ability to try new tools/practices/crazy ideas that would be immediately shot down at most other places. Open source friendly, allowing you to let some of the most interesting work shine publicly which can be great for career growth. Very open/honest communication about performance, sales, and financial stability for the company. Solid core product as evidenced by the extraordinarily low customer churn. Fair compensation, flexible policies, and really great office/location/amenities.
Cons
Open office environment can be distracting for some types of work but this is unfortunately becoming the norm in many companies big and small. Although well established, the company has a very tech-startup culture that often causes struggles for non-technical roles. Any tech person with startup experience would be comfortable though. Hiring practices tend be too "pedigree" heavy which can lead to pushes by upper management to hire someone with the right schooling/work history/connections but ignoring their actual accomplishments/abilities/culture fit. Such hires tend to have big egos causing resentment and churn. Some performance communication can be done too publicly which causes morale loss. Sometimes hot technologies/ideas are chased on a whim with little market research. Great for learning but not great for revenue growth.