Pros
I've had a good experience with Appian, everyone at least that I interact with is very willing and excited to help you gain experience and grow in your career, which I haven't always experienced at other jobs. Good culture, great flexibility, good work life balance (In my department at least it isn't expected to work weekends or past 5 etc). As long as you do your job and do it well, you will be respected and won't be micro managed. It's nice to work at a company where everyone (for the most part) is very competent and responsive, which of course makes it easier to do your job well.
Cons
The company is growing and of course there are growing pains that come along with that. However I don't see it as necessarily a deterring factor. There's a lot of experience you can gain within this environment of growth, just if you're not willing to keep up with it, it isn't the environment for you. At one point it did feel like we tried to 'do' too much at once, however I think we learned from it and things are better, and it really didn't take long to recognize the need to slow down. I really do enjoy working for Appian and feel that my work is valued as well as my personal requests (in terms of work life balance, time off, if there's too much on my plate, etc) are respected. Also I have to give the CEO credit for being willing to adjust his expectations (for a lack of better terms) during the pandemic in terms of remote work etc.