Pros
most people are nice and keep to themselves. very frequent social events for "team building"
Cons
The biggest issue as is anywhere: favoritism and blame games, but amplified because it's a small startup. There are chemistry and yield problems, but they'll point fingers at others instead of looking at the fundamental issues. Particularly, there's one today applications engineer who doesn't do any work and brags about how smart he is and then turns around to harass everybody else. He's the one brown-nosing all day with the executives, of course. Then he'll rope you into doing his work and walk away and blame others for falling behind. They'll easily layoff people so that promised stock offer IPO is dangled but never becoming a reality.