This is a super easy way to include an index of a specific taxonomy on your site, and we've been using it for quite some time now. We post fiction recommendations and reviews, with the author names in the tags, so this plugin provided a super easy way for our readers to browse all their favorite authors and discover some of our older posts about their stories.
The only reason I'm giving it 4 instead of 5 stars is that we had a recurring problem with the list reorganizing itself. Where it was once A-Z, it would occasionally start with D's, stay in order for a few letters, and then skip to something else. The tags were still in the correct order under each letter heading, but the letter headings themselves were jumbled. It was still useful, so we never got rid of it, and it seems to have sorted itself out -- for now.