I need a .Net ORM, and I heard some good things about this. I've had NHibernate running in the past, but this seems to make a lot of things easier.
However, two things made me a little nervous.
Is anyone using it, and do they recommend it for a production environment? Is it still under active development?
Specifically, is it worth it to use ActiveRecord over just plain 'ol NHibernate?
It violates domain-driven design because it forces you to add attributes to your domain objects and use the active record pattern through them, which ideally should remain simple POCOs. The rise of domain-driven design over classic 3-tier design means that it may not be a good library to become familiar with over the long term (maybe go for nhibernate straight up). On the other hand, it's an excellent and robust library to use, and the project that I used it on was a success.
Yes, it is worth using ActiveRecord over just plain NHibernate, as it greatly simplifies configuration.
They have nightly builds of Castle which is compiled agains NHibernate 2.0 or even 2.1 as of now I think. Few people uses the RC3, and I believe a GA-release is to be expected soon.
However, even though ActiveRecord greatly simplifies configuration, aswell as ease up the usage of NHibernate even when querying etc, I've experienced that most of the time I still fall back to using NHibernate-logic in code, therefor not taking advantage of the other aspects of ActiveRecord (especially when it comes to 2nd level cache etc which afaik ActiveRecord doesn't support). Even HQL etc requires using plain NHibernate-logic to be useful in my experience.
Therefor maybe it's worth using straight NHibernate and skipping the ActiveRecord part unless you're building a pretty simple app where performance-tuning really isn't an issue, since you have various other configuration-options to XML nowadays.