Seems like it's useful mainly for simple Create-Retrieve-Update-Delete applications... the kind that MS Access will generate for you with a wizard. The whole idea of declaratively defining a middle tier in this way basically negates all the advantages of J2EE: distributed, componentized, heterogenous clients, (distributed) transactions, etc. I get the impression that Aspire isn't suitable for creating ColdFusion-class apps, much less your average J2EE app.
J2EE was designed to solve hard problems. If you're only going to attack the easy problems--i.e., the kind of problems where you can get away with having all the data in the database--then I'd say you're probably better off going with PHP or ColdFusion or whatever, than applying this type of facade over J2EE.