Rated 4 out of 5 stars

StumbleUpon is just great, and the toolbar is the perfect app to waste hours and hours of surfing the webs... its functionality might be better, and I can confirm a certain slowdown & stability issues, but overall, it is a must have for stumblers.

This review is for a previous version of the add-on (3.76.1-signed).  This user has a previous review of this add-on.