Pros: Work with cutting-edge tools and languages. Work with people who basically know their shit. You're given much more responsibility, hence control, upfront. Process isn't ossified. Flexible hours.
Cons: Hope you like your coworkers because you'll be working cheek-by-jowl with them in someone's coworking space or crammed in a garage or something. They will try to pay you partially or entirely in Bison dollars (equity). You are assumed to have flexible hours so I hope your evenings and weekends are free. A company without solid footing can go tits up once the VC funding dries up, sending you on an early job search.
Cons: Hope you like your coworkers because you'll be working cheek-by-jowl with them in someone's coworking space or crammed in a garage or something. They will try to pay you partially or entirely in Bison dollars (equity). You are assumed to have flexible hours so I hope your evenings and weekends are free. A company without solid footing can go tits up once the VC funding dries up, sending you on an early job search.