If you use xmarks or firefox sync as well, then icloud bookmarks will keep fucking up your bookmarks. Even after a reset (disable icloud on all devices, deleting all bookmarks, reinstalling icloud, restoring bookmarks) after a while icloud bookmarks extension throws in tons of duplicates. But I need icloud bookmark sync because I have an iphone and ipad as well and I prefer to use safari instead of firefox for ios. Never had any problems using xmarks or firefox sync (on windows as well as linux) but with icloud bookmarks and photo stream I have had nothing but sync problems. Apple=expensive rubbish!