Very easy to install the module (remember to also install the 'anywhere' plugin too to have Fancybox operational on individual Joomla pages). I had it up and running in a few minutes and the included notes answer most questions you're likely to have.
The one problem I encountered (a conflict with my own Joomla template) was answered and solved by the support team within the hour
It would be nice to be able to run the detailed images as a slideshow as well as regular images (currently only previous and next buttons are available). Also the ability to add/edit image info from the front end would be helpful.