What do you like best?
Taking into account that his main rival SQL server has a lot of limitations, I would say that Oracle is the only option if you have to manage big databases with high availability and good performance.
Also for Big Data projects I would not consider more options, and I would go for Oracle Exadata.
What do you dislike?
Well, it is not a drawback itself but Oracle is big, huge... So be able to control all its areas it requires a lot of effort.
In my opinion is better to focus on some areas only (admin or developer or tuning...)
Recommendations to others considering the product
Big projects require big and trustable solutions.
What business problems are you solving with the product? What benefits have you realized?
Like I said, for big Data projects is the best option. Personally I still don't trust 100% in no-sql solutions, so Oracle is a must.