Pros
Fast growing company that works in an interesting industry. Nice to work on a product that is about solving real problems for real businesses. I've heard it's a happy place outside of the engineering department. They will probably continue to grow successfully for the next 5 years.
Cons
The company is perpetually plagued by the inability to deliver new software products. Big ambitious projects are started, inadequately staffed, mismanaged, and then abandoned. A few months will go by, and then upper management will rename the project and try all over again. This endless cycle of creation and destruction has gone on for years, and has demoralized and gutted the engineering org. It has been like this for the past 10, and will probably be like this for the next 10, as long as they still have VC money to burn. The culture of the company is built around salespeople, not engineers.