Rated 4 out of 5 stars

For some reason, this extension includes a (long since fixed) bug I reported last year in the original Thumbnail Zoom -- the zoom panel doesn't respect the user's page zoom setting. I browse at 200% zoom on my TV using "NoSquint", and because Thumbnail Zoom Plus displays images 1:1, they often appear smaller than the original thumbnail. When this issue is resolved, I'll gladly upgrade my rating to five stars!

This review is for a previous version of the add-on (1.5.8.1-signed). 

Good idea; in 1.6.1beta1

This is implemented in 1.6.1beta1, here: https://addons.mozilla.org/en-US/firefox/addon/thumbnail-zoom-plus/versions/