Pros
There is a lot of energy at the company, which comes from the passion of the employees. Everyone loves theatre, and what's more, loves their job and helping people around the world to make theatre. This energy lends itself to having a great company culture, complete happy hours, fun activities, treats for the office and more. Samuel French is also very plugged into the the theatre community and industry; if you allow yourself to open up to the outside opportunities that the company offers, you'll learn a lot about the industry and start making terrific contacts.
Management also actually listens to the employees' concerns, and (slowly, but surely) makes changes that positively affect the company and culture. If you are good at your job, have enthusiasm and passion for the work you're doing, and are loyal to Samuel French, there is doubt that you will grow here - and not just within your own department. Since the company is a smaller one, employees who are interested in different departments can apply to available positions and are often moved, if their skill set meets the criteria. It's a very supportive office, with the directors and managers showing a lot of encouragement for their staff to rise up.
Also, the work life balance is terrific. Obviously, there are times that are more stressful than others and late work nights can occur. But from my own experience, when I am working late, it's because I want to be there and love what I'm doing.
Cons
Sometimes, the "let's have a fun office culture" can feel ever so slightly forced. It's actually gotten quite better over the past few years, but feels like it is still working out the kinks. That being said, in my opinion, it's better to have a fun, if not sometimes stressed fun, culture than no culture at all in the office.