Pros
Employees have a very large autonomy. They are able to work on very diverse and challenging technical topics, and they quickly get in charge of important projects. It's a good way to start a career
The work atmosphere is very friendly and pleasant
Cons
The company needs a lot of money to develop new projetcs, but face a lack of capital that will not threaten the company but may hamper its fast growth.
You also get lower salaries than in a big company and less advantages.