been using it since it started. a little skeptical since it's my data being hosted "in the cloud." but it works well. They need a purge all history option though. As it stands, if you want to wipe your cache, you have to do it for each file/folder.
but I've started using it so I can access my password file at work. I just use truecrypt to put a small container for the file, have it password and keyfile'd, as well as the password file.