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 used it for a project a couple years ago. But when the project was done, I couldn't tell anyone what CSLA did for me. Sure, I inherited from its classes. But I was able to remove that inheritance from almost all classes with no restructuring. We had no use for the N-Tier stuff. The n-level undo was so slow that we couldn't use it. So I guess at the end it only helped us model our classes.
Having said that, other teams have started using it (after a horrid attempt by a team to create their own framework). So there has to be something worthwhile in there, because they're all smarter than me!