Pros
Guidewire hits the sweet spot between "startup culture" and "big corporate culture." There is the small company vibe, wherein you can talk to everyone and get things done. And there is enough room for flexibility in processes for individuals and teams to choose what works best for them, while having the support of the larger organization.
Development has a bunch of really smart and talented individuals who are a pleasure to work with. Management is not directive, but is supportive and encourages constant feedback.
Guidewire has built a bunch of great products and is constantly innovating to solve customer needs.
I look forward to coming to work every day.
Cons
I cannot think of any cons for Guidewire.