I'm an occasional, rather than compulsive, user of del.icio.us bookmarks. Nonetheless, whenever I reinstall FireFox, the del.icio.us toolbar is one of the few extensions I install automatically. I did this last week after reinstalling FireFox on one of my Linux machines. The installer seemed to have been updated from last time I went through this operation, but hey, stuff changes. Clicked OK on the buttons yada yada. Got the new del.icio.us Firefox extension, and boy has it changed.
So what does it do? Well, it uploads all of your FF bookmarks to your del.icio.us account, then replaces the FF bookmarks menu, and sidebar with its new, better version. All of your bookmarks are still in there, somewhere, but they appear as del.icio.us bookmarked entries. As a side-effect, if a given URL is already tagged by other users, you'll get those tags for free. So that's kind-of nice. What totally sucks is that the process throws away your existing category structure. Now, I'm the first to admit that I tend to the overly analytical. My Myers-Briggs is INTJ. My bookmarks are nested in folders up to four deep. The frequently used ones are near the top of the hierarchy, but, most of all, I know where they are. Once I'd del.icio.us-toolbar'ed my bookmarks, all that structure was gone. I was left with two flat lists, one of 980 bookmark URL's and one some several hundred tags that apply to those bookmarks. There is a category structure you can build (del.icio.us calls them bundles), but it only applies to tags, not bookmarks. So there was no way to manually re-create my nested structure.
From a usability point of view, the tool bar is nicely implemented, but, for me at least, completely unusable. I imagine that if you have a user whose bookmarks are already in one thumping great flat list, the auto-tagging feature will add some discernable value. For me though, it was a massive step backwards. It's a shame, because I believe in the value of metadata. The problem is that you really make people work to find stuff they've added. I don't want to have to type in search terms to locate the bookmark to my local weather forecast.
A saving grace is that uninstalling the extension gives a dialogue that offers to restore your bookmarks back to the way they were. This worked seamlessly. Apparently, the "classic" version of the toolbar is still available, so I'm going to try to track that down now.