Avantages
Great, smart, educated people with whom you really want to work, who are ready to discuss, support and help you.
Inconvénients
Very soon you will be stuck with your salary and title. It is not impossible to grow further, but you really need to be luck, working hard and show yourself at the right place at the right time (the luck is the most important thing here). This is a company of "wheel inventors", instead of using already tested, reliable solutions and frameworks, which can be de facto standard for industry, everything must be implemented from the scratch. It can be good at the begging to understand how it works for junior developers, but it is definitely not reducing the cost of development and further maintenance. People treated as resource, not as human. But it is only for high level management, which is always telling that we are the one big family, but nobody actually care about your family, your personal life and your personal opinion.