I’ve been trying to work with Ubuntu One on my two Ubuntu 10.04 amd64 computers. I’m glad I’m trying the free version because it’s very painful. Bookmark sync doesn’t appear to work at all.
Update: I fixed my problem with the Firefox Bindwood extension. Apparmor seems to have been causing the problem there.
Update 2: Canonical’s status page for Ubuntu One says that there are problems syncing bookmarks.