Pros
This was my first job out of college and I didn't know what to expect, especially with COVID. Although I developed many gripes and internalized angst through the years, there are many reasons Appian can be a decent place to work. Excellent work-life balance (for most positions). Company is large enough that most work can be split or pushed off, and because of unclear initiatives nothing really gets done outside of client work if you're in Customer Success. As with most companies, the people at lower levels and even some upper management are decent humans. If you're looking to take things chill and aren't expecting too much in terms of bonuses or promotions, Appian is fine.
Cons
Oh boy, my favorite section! Company has the same issues as any that don't run a tight ship with an eye on management effectiveness. Promotions are tenure-based, top talent leaves, and management doesn't know how to communicate (then again, most people don't). The product isn't great, which is probably why they've had so many issues recently. You can note the stock drop from ~$215 to ~$30 largely due to overvaluation. Company doesn't know how to leverage people's skillsets. There are so many internal tools built out to make this happen, but no one pays attention or uses them.