At the MVP Summit, Daniel Simmons met with me and many other MVPs including other CodeBetter folks.  One of my issues with the Entity Framework was that my domain classes would have to have so many artifacts tied to the EF.  Attributes, interfaces, event calls, etc.  With NHibernate, my domain classes don’t even have a reference to the NHibernate library. 

Daniel has recently posted something that everyone should read.  Here is an excerpt:

“Initially I thought that some of the requests for *complete* persistence ignorance were the products just of dogma rather than fully informed and reasoned arguments, but when so many people give such passionate feedback it was clear that I needed to investigate more before I could claim to have any sort of an informed opinion.  The product of my research is that I am now truly convinced of the importance of complete persistence ignorance for some scenarios.”

Bravo.  http://blogs.msdn.com/dsimmons/archive/2007/06/02/persistence-ignorance-ok-i-think-i-get-it-now.aspx