Pros
1. Environment: Relaxed and chilled environment, you would feel no (less?) stress but which doesn't mean low productivity, instead people being flexible to behave in their own way to work for productivity.
2. People: Young, talented and inspiring! Yes young people are all friendly and easy to hang out with. No one acts as they are the coolest in the office!
3. Flat hierarchy: No one has their own room even the CEO. Everyone shares the open space! Your team lead acts as a captain instead of a coach. They play the game together!
Cons
1. Still a startup : Sometimes you may just find something being inconsistent, anyway it's understandable that we are in the midst of stabilizing the system. That's the spirit of a startup!