Pros
It is one of the best small MEP firms in North America with a unique building science perspective. It is incredibly supportive of its employees and provides opportunities for professional growth, technical growth, and career development. The team is small and inclusive. The pay is excellent, on par and above competition. The types of projects the firm works on are absolutely unreal, this is a unique place to be.
Cons
The nature of small firms means that everyone is rowing the boat. There are not the formal infrastructure elements that large firms have. This means that certain personality types will do well here, while others will not. It entirely depends on what kind of employee you are and how proactive you are, as well as your ability to manage complexity and your time.