yes i did several tries with prism. It was ok and it was running and i liked the region manager. But it is so complex that i spent a lot of time to check the documentation and care about the mef annotations and so on that i started searching other frameworks.
Caliburn.Micro was my first idea, but i found not really good examples for my wpf desktop app in a business case. Because of any articles in a magazin and at msdn i decided to try MVVMLight. The documentation is even not so good and their are a lot of examples for windows phones and not really for wpf busniess apps but it is easy to understand, lightweight and for me it seems to be the right choice in the moment. I like the the ServiceLocator to integrate DataService in the design time and working with Blend 2012.
Perhaps that can help you:
Here the Laurent is talking about two of the key features of the framework.
If you have any interesting links or sample. Let me know pls.