Mon,
I am using Mere Mortals. The one thing I can say about it is that the support is very good. Kevin McNeish is very good at replying to any and all questions and requests that I have had.

The product has a really good Jump Start Guide and is very well documented. It definitely supports N-tier development with business objects. As far as how it compares to other frameworks, I really don't know.

If a developer has never used a framework before, I suggest they do it. If you don't want to use it for your actual production, do it simply for all the knowledge you learn. I have learned a LOT of things simply by learning this framework; things that I never would have learned had I stayed with my own tried and true code and framework.