In the last time I heard a lot of complaining about Hibernate. And indeed I have some painful experiences with Hibernate too. So I read about Ebean and Siena.
Both have interesting approaches. Unfortunately, database access layers are very easy to write, but if your project grows and you have to handle great database-tables, you know if they are good or not. So it's really difficult to evaluate such a tool. Hibernate is well known and you could be sure that you can solve your problem with it. Sometime you need to learn a lot, but you can solve it.
How is it with Ebean? Are there any real world applications? Which databases are supported? Is it reliable?
After searching a little bit more I see that there are a lot more ORM-frameworks, so is there at least one reliable one?
Rob (Ebean Committer) here.
Ebean is about 4+ years old now. I would say it is fairly mature now. The supported DB's include Oracle, MySql, Postgres, H2 and SQL Server (and recently SQLite). Ebean is doing stuff that other ORM's are not such as Autofetch (automatic query tuning) so I'm not how that fit's into a 'maturity rating'. IMO the Ebean community is relatively small though so you probably need to hit the Ebean google group to engage them.
Any real world applications? Yes, but you are best to ask the Ebean community about that really. Certainly there is good support for batch processing (batch size, turn of cascading persist for a transaction etc) and large query support that I don't see in JPA etc (you might get something similar with Hibernate's Sessionless support).
Hopefully this might answer some small parts of your question anyway.
Cheers, Rob.