UPDATE: Philippe has been great about fixing things, and has fixed the data loss in the new Beta version, near as I can tell. Since CardBook is going to be a very good add-on, I'm changing my Rating for it.
OLD REVIEW BELOW:
*** DATA LOSS ALERT ***
And yes, I will contact the author about it as soon as I post this here.
CardBook is a potentially good addon, with (so far) a pretty serious data error in the concatenated (lumped together) Email and URL fields. This bug DELETES data from Email (No Type) and URL (No Type) - and possibly from the other URL fields - and stores the deleted data ONLY in the concatenated field. It does not put the deleted email addrs and urls back in their original fields when exporting. They are trapped in the CardBook concatenated fields and would have to be copied out manually one at a time to export them or back them up into another format. If you can even figure out which email addrs and urls are the deleted ones.
The Name fields are also concatenated - but in this case it's only for display purposes, no data is deleted, and all the data exports just fine. The author very probably intended the Email and URL fields to work the same as the Name fields. I.e., without any data loss.
A program that deletes your data should not be used, so I'm sure the author will fix this issue ASAP.
This review is for a previous version of the add-on (33.4).