Pros
Appian has some of the smartest and most motivated people I have seen. The majority of people know what they are doing and are pleasant to work with. Appian takes pride in its rigorous process of hiring to make sure that people joining the company have what it takes to work with smart people and contribute to the overall culture and success of the company. One learns many skills in a small company that help grow one's abilities beyond what typical large organizations offer.
Cons
While it has been impressive to see the tremendous growth in a down economy, which is a testament to Appian's management and ability to deliver, the communication from the top down is a bit sparse. As such, if you're not in the upper ranks, you have a less of a pulse of how things are going. Nonetheless, it's better than past years.