Great, time saving extension! Rated 4 out of 5 stars
This is a wonderful extension. The recent added capability of grouping speed dials is incredibly useful. Drag and drop organization of groups, sizing of thumbnails makes accessing your most used Web pages beautifully simple. A real time saver. I anticipate using Speed Dial instead of FF's built in book marks as soon as I can get them all organized.
The only downside I can think of (which isn't a problem for me) is that configuring it might be a little difficult for newer users. My suggestion for new users is not to miss out on this extension. Check in on the discussion section here for problems you have with it. Chances are, there's either a solution, or a workaround for it. Don't let your "newbeeism" scare you away from this extension. Once you learn to configure and use it, I think you'll find your effort was well spent.