Pros
Work culture, people and environment is very understanding and respectful. The company has good core values and treats its employees well. Work-life balance is great. Depending on what you work on, you could be at the bleeding edge of the most exciting technologies in the market. It's a very grass-roots organization where ideas are primarily formed and nurtured bottom-up rather than being pushed top-down. This gives a lot of power to technical engineers and staff.
Cons
Not the best paymasters in the area but quarterly cash bonuses make up for it handily. Being a privately-held company, I've always wondered how it affects decisions made in the company. For the most part I think it has helped in maintaining focus on the right places to invest in. But at hard times, resources can get tight.