The main web application of my company is crying out for a nifty set of libraries to make it in some way maintainable and scalable, and one of my colleagues has suggested CS
I've used CSLA.NET in few projects now, it was most successfull in a windows forms application which has rich databinding compatabilities (which asp.net application's don't have).
It's main problem is the TDD support like people have been pointing out, this is because of the black-box like behaviour for the Dataportal_XYZ functions and it's inability to allow us to mock the data objects. There have been efforts to work around this issue with this being the best approach