Original post is here: eklausmeier.goip.de
I have been using del.icio.us (dead link) since at least the year 2005. During that time del.icio.us (dead link) was sold to Yahoo, which didn't do very much with this bookmarking service. It simply worked. In 2011 the service was acquired by a company named AVOS (dead link), see Wikipedia for the story. Since that time the user interface was changed, using more JavaScript/AJAX, many previously working functionality was broken, service was down repeatedly, many login-problems, slow response times, server errors (HTTP/503), export not working, deleting or modifying URLs not possible, etc.
I have been searching for a good alternative, but haven't found one which really satisfied me, despite all the hassle with AVOS (dead link).
I am now considering to enter, or at least regularly backing up my URL's directly here in WordPress, see collected-links. I now regularly export my bookmarks to file, so to not lose any data. This export file is then run through a Perl script named delicious. This output is then manually put to collected-links.
See my post Migrating from delicious.com to WordPress.
Addendum, 27-Dec-2014: Exporting bookmarks via Export Bookmarks (dead link) does not work, you get the message "502 Bad Gateway". As stated in their blog (dead link) at May-8, 2014, Delicious is now owned by a company named "Science". It looks like they want to scare off any users.
Added 22-Apr-2017: Company "Science" apparently has lost interest in del.icio.us, it is now owned by a company called DomainerSuite.