Pros
Coworkers genuinely seem to care about each other. The tech was solid, and our small engineering team (3 full-time / some outsourced contract work to India) quickly developed into a cohesive unit capable of producing enormous amounts of well-tested code way ahead of schedule. Our CTO was an amazing leader and continues to be a close friend and advisor.
Cons
The stats about husband-and-wife cofounders are true. Our development team was in one room, toiling away, while the CEO and his wife (CPO) brought their personal issues into the office with them. The CEO was very well qualified, but his wife had essentially no relevant experience with product development in tech or any other area. I could go on about this for hours, but think it is sufficient to say that the tension eventually became unbearable, and I sought another opportunity.