Upserting, typesafe queries instead of raw strings, disconnecting my domain model from jpa, disconnecting my domain model from validation etc. It's also really

Upserting, typesafe queries instead of raw strings, disconnecting my domain model from jpa, disconnecting my domain model from validation etc. It's also really difficult to use an EntityManager outside of a JEE/Spring/framework container. They're not thread safe and you have to manage their lifetimes manually.