I'm a big fan of Bookmark Toolbars and the way I use them is I delete the name of the site so I just have a line of nice looking icons/favicons to my top sites. I find this far faster and generally more elegant than any kind of standard side panel bookmark system, though I will say Opera's bookmark system is a novel approach, but it's still cumbersome. A panel or seperate page popping up just to get to your bookmarks is uncessary and the idea that I'm going to remember the names of them all to search via the location bar is just... unrealistic. We need easy visual access to bookmarks and that's why Bookmark toolbars are nice.
The only downside is the Bookmark Toolbar is pretty limited in total size, but folders more or less eliminate that problem up to a reasonable degree. Using a combination of Favicons without text and your drop down folders on the Bookmark Bar I can easily fit 90% or more of the bookmarks I actually use right on the Bookmark Bar. They are right there for me to get to anytime, they are there to remind me of any sites I might otherwise forget I wanted to go back to, and the interface is very straight forward as well as fairly standard across all browsers.
For the sake of a nice consistent look I would like to be able to set the Icon for a folder that I put into the bookmark toolbar. This way I don't use up my precious Bookmark Toolbar real estate with text. It also looks nicer.
It would also be nice to be able to adjust the size/spacing of those Favicons. These should both be very easy to code and personally I think people are missing out on the use of Bookmark bars. Toolbars got a bad rap over the years due to all the malware that would install them. The bookmark bar is also quite small so I don't find it a concern for taking up vertical real estate. The time it saves and ease of your bookmarks being right in front of you as a visual reminder is well worth that thin line of space being used up because bookmarks are quite important. There is just too much info out there to not use bookmarks and not constant forget sites you meant to read or instructionals you will need later.
That all being said, I'm highly impressed with Opera these days. I had kind of written it off, but it's now one of the best looking browsers around and generally very easy to use.