1) Project development cost is reduced.
2) Used best JDBC concepts such as:
a) Batch operations instead of individual operations
b) PreparedStatement instead of Statement
c) Rowset instead of ResultSet
d) DataSource (connection pooling) instead of DriverManager
3) Managing associations such as one-to-many, etc is simple as working with collection properties like java.util.Set, List, Map.
4) No memory leaks since resources are automatically released by framework.
5) Being ORM framework, the Hibernate will get all its befinits:
a) object becomes record and vice versa
b) Supports multiple primary key generators
c) Supports Second level cache
d) Additionally supports Object Query Language (HQL)

I didn't get this one:

Rowset instead of ResultSet

Check out this StackOverflow answer as well.