I didn't really understand what the company does and there brochure made it sound like their technology was interesting so I applied. Questions are somewhat harder than average but manageable. I'd say half of the interviewers were very nice but the other half felt very snobbish.
The onsite started with a product demo. The gist is that Addepar serves "ultra-wealthy individuals" and builds web apps to manage their assets. I immediately get the feeling that as an engineer my job is pretty much cleaning the messy data collected from these rich guys' various banks/funds/whatever and present them in a nice format. I proceed to finish the interviews and correctly solved all the problems but I really lost interest in working there from the first minute.
In summary, it's a decent place to work as an engineer. But if you are looking for something challenging to work on, it's probably the wrong place. (To give you an example, one round is to find a bug in a HTML parsing library. I did it in like 2 minutes and the interviewer made it sound like when they found it, it was some kind of major engineering break through. Good job, guys.)
p.s. Catered food on the interview day was pretty bad but I can't complain about free food. Maybe I hit a bad day.