Nothing of this matters (to me) anymore since Google Plus was born. I believe it's now just a matter of time until all the rest gets merged into it.
To me, bookmarks were simply a way to mark what I like and maybe being able to find it later. Most of the times, I wouldn't ever bother about that link again and my bookmarks would just bloat up.
I never really organized or categorized and, even if I did, links would easily get broken after few years.
So, G+ is a way to mark / favorite / bookmark links in which I can easily see and find them again if I need to. Plus it is meant to work exactly as described, with the addendum that it will also show up on my search results and shared with my circles. The only thing lacking here is the ability to sync with my chrome bookmarks (which I don't use any longer) and google bookmarks. Both should probably be merged somehow, eventually.