Pros
Solid company with current technology. Regular equipment refreshes, multiple large monitors, good location (for me), modern email system, easy to get lunches.
Good coworkers. Relatively high hiring standards.
Company works well together and coordinates to get new business and grow the firm.
I have personally recommended my friends to work here and some have joined (but some didn't make it through interview process which is fine).
Customers are solid.
I worked at a couple other software firms prior to joining Appian.
Cons
Competitive industry keeps pressure on the company to perform. Little name recoginization outside of the industry.