Vantaggi
Oracle has an excellent software development team in the server division. The average quality of the developers is surprisingly high for a mature company of this size. There are a substantial number of world-class people there, although perhaps not in as large a concentration as 10 years ago, due to long-timers retiring and losing a lot of the best young talent to places like Google, but it's still a lot better than Sun was at its peak. The scale of software development at Oracle dwarfs almost anyplace other than Microsoft, and the engineering culture is, to my mind, far superior.
Svantaggi
It's a huge company, so it's hard to stand out sometimes. There are politics, but they aren't crippling. I worked at a number of smaller companies, and any of the other places with more than 100 people had worse politics and worse outcomes. While I worked at Oracle, they would have "bake-offs" when there were conflicts about how things should be done, and the best code would win. Being involved in one of these is a lot of pressure, but you can actually win just by doing a good job. You also have to learn to think a little outside the box - but not too far - to make useful contributions, and your boss needs to toot your horn in order for you to be adequately compensated.