Originally Posted by plienas
The downloaded metadata tags are usually not much of help (currently i've imported 100 books and have over 300 tags -- not the most useful tool to help browsing the library). Problem -- too detailed, too many of them. Although they are helpful then sorting the books manually.
I'm afraid I can't help you with categories, but I had this problem with tags too. I now have 10000 books and only 240 tags. I use the Goodreads metadata plugin to retrieve tags. This plugin allows you to map the Goodreads genres to the tag names of your choice. This way I have a finite set of predefined tags. I outlined how I use this plugin and my mapping in this post