Pros
It's hard to start a business from scratch, esp under the pressure of satisfying customers and investors.
I credit the co-founders in their willingness to listen, learn and their efforts to grow a team of committed, determined collaborators.
I joined because I want to contribute to doing some good in the world. That's a lofty, some might say naive or even arrogant goal, but I believe we've a chance to make a difference.
It'd be foolish to think that'll be easy or without challenges.
Cons
Learning curves can be hard if you're not up for the challenge. Hitting big goals is hard.
If you ARE up to the challenge it's also rewarding.
You shouldn't expect the highest salary or the most perks, but that's not what it's about.