Cool GM creates open and welcoming work environment. Basically GM creates the great work culture. If this GM leaves the culture leaves with him.
Inconvénients
You have to be independent and know what you are doing before starting with a company, since there is low amount of training provided. They will give you work outside of your scope and responsibilities with no additional training provided even if you ask for some.
Also they also have very sexists approach regarding pay for the same amount of work and education.