Pros
The main advantage of working in Oracle is that there is an opportunity to practice very interesting computer science in a "normal" environment. By normal I mean that there is no pressure of releasing a new customer-facing product every week. Most of the products have a one or two year development cycle with a couple of minor releases in between. My colleagues and managers were mostly very friendly and I enjoyed my stay.
Cons
There were a few architects though who tended to act extremely arrogantly. The more important their position the more rude and arrogant their behaviour. It is quite puzzling why they were tolerated. The company tends to be very stingy about giving basic perks to their employees. Even getting necessary hardware resources can be quite a battle.