*Leverages large persistence library to avoid developing solutions to problems that others have already solved.
*Avoids low level JDBC and SQL code.
*Leverages object oriented programming and object model usage.
*Provides database and schema independence.
*Most ORM products are free and open source.
*Many enterprise corporations provide support and services for ORM products.
*Provides high end performance features such as caching and sophisticated database and query optimizations.
Reasons for JPA
*It is a standard and part of EJB3 and JEE.
* Many free and open source products with enterprise level support.
*Portability across application servers and persistence products (avoids vendor lock-in).
*A usable and functional specification.
*Supports both JEE and JSE.
Most of the points above directly/indirectly help improve manageability
CRUD like opertaions can be taken care entitymanager hig level api, no need to write basic queries, m:n relationships can be managed via configuration, check out query generated for these associations .. its cumbersome to write and maintain in JDBC ..