Rated 3 out of 5 stars
It works very well, but needs three additions. Right now, it creates a catalog of EPUB volumes automatically, and adds any volume you read to it. The catalog lives in the profile directory. If you have more than one FF profile, customized for different purposes, like I do, and you want EPUBReader installed in all of them, you have multiple, out of sync catalogs.
It should be possible to not have a catalog at all, to choose not to add a volume to the catalog if you have one, and to specify where the catalog is created so it can be shared between profiles if you choose to have a catalog.