The company culture is unique in my 30 years experience of working in software in the Midlands. It's (almost) free of internal politics, full of very bright people who largely have fun. Work is challenging but everyone is supportive of each other. The employees have a substantial shareholding in the company.
Lots of very sharp people, with a rewarding blend of technically challenging work and a supportive environment. There's a very strong focus on personal development, and the company is getting gradually better at properly delegating responsibility.
Cons
There have definitely been growing pains as the company has got larger, older and multi-national, and it feels less cohesive as a result.
Bonuses have been very lean recently, and there's some concern about salary competitiveness for specific groups of employees.