JPA vs Low Level Datastore on App Engine

I am getting into App Engine development right now with Java and I am wondering what people think about using the low level api instead of JPA? I understand that JPA may make the solutions more portable in the future but I don't anticipate taking my开发者_StackOverflow code anywhere else.

Is it ok to use the low level api instead of JPA? I'm interested in hearing the pros/cons of each method.

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I woud perfer a clear API like jdo over direct use of datastore There are new article serie with nice examples form Google self at http://googleappengine.blogspot.com/2009/12/jpajdo-java-persistence-tips-year-in.html

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Why choose one or the other? I would choose a higher level abstraction that's documented (JPA or JDO) and the low-level API where the high level abstraction falls short.

Keep in mind that the API still seems to be a work in progress so if you choose the low level API exclusively, be prepared to roll with the changes.

I found JDO to be easiest to work with and haven't had to resort to using the low-level API yet.