I rarely write reviews for an addon, but this addon is just so awesome for something so simple. First, I don't use the breadcrumb UI in the location bar but it looks pretty cool at a glance. However, I absolutely LOVE the page loading progress bar animation. It absolutely modernizes Firefox, especially when combines with Australis curved tabs in Firefox 29. Looks very slick (and very useful)!
The only thing I can think of that could improve this great addon even further is if the progress bar loading animation can be 3D. That would make it even slicker! =D
Thank you for making this great addon!!