When it comes to breaking down the advantages and disadvantages of Oracle database you have to start with the fact that Oracle is the world's largest enterprise software company.  Larry Ellison founded this company on certain principles and he has continued to be the market leader by abiding by them.

One of the main advantages is reliability and adequacy of the database upon four major elements.

Atomicity
For the results of a specific transaction the execution ais either all engaged or retracted.

Isolation
The transactional results are not visisble to other transacts until the transaction is finished.

Consistency
Databases goes from one valid state to another valid state.

Durability
Results of a transaction have permanence.

Oracle continues to acquire other competing companies that accel specific areas to improve on its products.  That is another major advantage.