Depends what your needs are. If you're mostly using one browser on one machine you're fine.

Need something that's cross-platform, cross-browser with arbitrary tagging and suddenly you're looking at third party service.

Add to that the discover side of shared bookmarking tools (Gee - I wonder what everybody else has tagged with "foo") and a third party service is the only thing that will help.

I was a really happy delicious used before the post-yahoo rewrite. Then they lost about 1000 bookmarks of mine so I moved to pinboard - where I'm not quite unhappy enough to go write my perfect system ;-)