Pros
Genuinely friendly people to work with. Great people.
Some truly unique projects to work on.
Supportive line management.
Pleasant work premises.
Nice summer and Christmas parties.
Reasonably handy discount scheme.
Cons
Overly hierarchical. If something can be passed down the line, it will be, regardless of whether it is quicker for that individual to do it themselves.
Very pedantic at times over minor things, inconveniences, focusing on the side issues rather than the bigger picture.
Being a charity, a little concerned that money isn't always spent wisely.
Absolutely no chance of progression or development - a job with no hope of promotion or change.