Pros
Every day at work was interesting, I never had a day where I was bored or didn't know what to do. The problems the company is trying to solve are technically challenging, lots of machine learning, high performance computing, and distributed systems. You have a lot of freedom to choose the tools you want to tackle a problem with, as long as you can make a good case for it. I learned something new almost every single day at work and got better at a bunch of stuff. There's a lot of opportunity for leadership and career advancement because of how young the company is. Hours and remote + work from home is generally quite flexible as long as you get your work done.
Cons
Hours could be long occasionally, but thats every early stage startup. It was never unmanageable.