If you're in the right role, the technologies you work with and the scale that you work with are hard to find elsewhere. You get to work with a lot of really knowledgeable people.
Cons
The company is too big. It's deeply impersonal and illogical as a result.
Sun used to be a great company: smart people and plenty of innovation. Laid back work culture. Plenty of opportunities to dive into interesting technologies.
Cons
Senior management never managed to get Sun out of the death spiral. The lack of insight at the VP level was startling.