Pros
Since it is a small company there are some great opportunities to be exposed to a lot of different types of work and a diversity of industries. Usually there are bonus opportunities for passing exams. Owner is very involved in the business and cares about his employees and their families. If you apply yourself you are rewarded and can move on to more interesting projects and more challenging work.
Cons
Since it is a smaller company it is common for the owner to work as a technician alongside his paid engineers and technicians (which means he is not able to be out growing the business or hiring talent to grow the business for him) Maintenance of the existing clients and sometimes being understaffed can lead to consistent but stagnant company growth.