I worked at RV as a Platform Engineer for 20 months before starting my own company and getting into YC. On the culture side, I personally enjoyed it as almost everyone was around the same as me and all were young and hungry to put in more work. On the tech side, there was always a push to get more done in less time. Constantly, there were super tight deadlines which resulted in bad code and then you just move on to the next thing without maintaining it. This would cause a lot of tech debt that was to be addressed, "when we had time". Overall, I still think RV was an awesome place to get started in (especially in the NC/SC area), then go work somewhere else and boomerang back into a more senior position.
I heard several times that he "Business reviews" were a mini MBA course, but I think there was more value in watching the way leaders freed engineers to creatively solve a problem, and then reigned them in just across the line of an MVP, to focus on something new.
It was very hard for me to understand the objectives at times, but it was clear eventually that there were diminishing returns in allowing the pursuit of engineering goals over business goals.
I learned a lot, even from outside most of the interactions I observed.