Pros
They really care here about keeping us happy and healthy. We get great benefits, including occasional "Mind, Body, Spirit" days where we have free massage and organize sports, dancing, yoga, surfing, music playing, or whatever the employees want to do. Our gym memberships are paid for. We also get one week each quarter to set aside the roadmap and work on whatever projects we want. We like each other enough that we really do enjoy the many company parties, and many of us hang out together outside of work-related events.
Cons
I always have a hard time answering this question when people ask during interviews. I guess sometimes I get a little frustrated when I'm working on something with a deadline and I keep getting hit in the head with nerf darts, but most of the time I like that there are nerf wars. People who don't like dogs would probably object to the fact that there's usually at least one in the office somewhere, but for myself, I keep dog treats at my desk.