Patrick Smacchia sent me this link where NHibernate 1.2.1 GA and 2.0 GA are analyzed with NDepend.
I want to you appreciate the analysis made with this tool, to see how much of details it offers to build comparatives between both releases. What I consider the most important is the analysis of the changes made. You will see in the picture with the blue zones, all the refactored parts, and you can arrive to conclusions 