I received an urgent request from my client to install a simple private messaging system. Finding uddeim has definitely been the best thing that could have happened. What I like:
1. The code is very well written and I have received no conflicts with existing scripts
2. 70 page documentation with FAQ. Saves me of pouring through forums for answers
3. Installs easily with no hitches
4. Up and running within minutes
5. Intuitive and easy to deploy
6. Integrates with CB (this was actually a requirement from my client and it was good to know that they had already thought of it).
7. Ability to create userlist. Very easy to do.

This is the first review that I have every written at this site and I whole heartedly this this 5 stars!! All the best with future releases and enhancements.