When activated this plugin conflicts with the code that is generated by WordPress' Add media functionality.
This is the code that I have in a post:
[caption id="" align="aligncenter" width="240" caption="Logitech MX Revolution"]<a href="http://flickr.com/" target="_blank"><img alt="Logitech MX Revolution" src="/images/screenshots/logitech-mx-revolution-annotated.png" title="Logitech MX Revolution" width="240" height="180" /></a>[/caption]
When I view the post, the referenced image is not visible and the code is sort of messed up. Note that this happens although I didn't use the custom fields in the post at all.