Well, there are a number of ways of mapping inheritance, and it depends on what types of benefits and drawbacks you're interested in dealing with.
Joined, Single_Table and TABLE_PER_CLASS are your three options for mapping inheritance with Hibernate and JPA.
I don't see anything wrong with this code, so I would say that it should work if it fits your bill. I've always been a fan of single table inheritance myself.
The single table inheritance type is often the best choice for performing inheritance mapping. First of all, it minimizes the number of tables that need to be queried, which can be significant for large class hierarchies. Furthermore, mapping associations can be very difficult with other strategies.
For example, imagine we were using a single class per table strategy, and we decided an Ancestor could be associated in a one to one manner with another type, say a Location type. Since this relationship would be true for all subclasses, and given the fact that associations are implemented at the database level by foreign keys, we would have to add a new foreign key column to every table that was based on a sub-class of Ancestor. In a large class hierarchy, adding those foreign key fields would be extremely onerous and error prone. On the other hand, with the single table inheritance strategy, only one column would need to be added to one table, which would be a much, much simpler process.