What do you gain from upgrading NHibernate 1.2?

Question

I have one project using NHibernate 1.2. I know it's old, but I've used it since I'm working off NHibernate in Action, which targets that same version.

I've been thinking I should update my understanding of the tool, as well as the tool itself. But I wonder what the differences are between versions. I know 2.1 has been current for some time, and that 3.0 is in the works.

What benefits or features are gained, lost, or changed when moving to NHibernate 2.1 or 3.0?

Answer 1

Off the top of my head and mixing 2.X and 3.0 features... LINQ support, EventListeners (more powerful Interceptors), System.Transaction support, generics support, multiquery, future queries, SchemaUpdate (rather than just SchemaExport), much better HQL parser, ... Plus numerous bug fixes. A lot has been going on in the NHibernate world since NH 1.2...