Pros
Nice people who will try their hardest to help you. A lot of ownership over your code, and the chance to work on very low level implementations.
Cons
The company has spent a lot of time working in its internal tech stack, mostly hiring either straight out of college or lifelong K developers. This has created a real dearth of industry knowledge and experience, with most of the senior engineers having spent most of their career at 1010 or writing exclusively in K. Problems are only ever dealt with in the 1010 way because it's the only way most people know, and newer engineers naturally can't bring a better perspective when this is their first job out of college. The tech stack is held back by needing to re-implement existing libraries ourselves in K. The technical debt of an entirely in-house system has created magnitudes more work trying to fix problems that have been solved more effectively elsewhere. Deficiencies in the system are mostly plastered over by the constant work of data devs, who perform client support that really should've been automated years ago. The company doesn't have on-call, but if you get assigned to the wrong dataset you will literally always be on-call because it will break in the middle of the night and you'll be the only one who can fix it.