Love the extension - exactly what I needed for the work we do. I would say that the documentation needs to be improved, especially as it's a commercial extension - screen shots of what you can type is pretty lazy, lack of a forum to ask questions and find answers to problems, has been an issue for me. I found that the extension stopped sending out emails, probably when the Joomla update came through, so I had to reinstall, purge the cache etc... It would be very handy to have at least an FAQs on his website.
Nevertheless, it's a brilliant extension, which should be built into the core.