DejaDup is quite a polished and solid applications:
- it handles several backup destinations (local or in the cloud)
- it uses the duplicity backup tool (itself built on rsync)
- it starts the backup quasi-transparently and doesn't need much user attention
- it makes it possible to restore backed up files with a simple click ((I happily haven't had to test this functionality so far))
- as it is configured in Ubuntu it copies everything in the home folder (except trash and custom selections of folders)
- it handles only one local destination (usually a symbolic link pointing at a folder on an external hard drive)
- it uses rsync directly and without much subtleties
- it warns the user when a backup is needed and guide her through important steps (like plugging the external hard drive, reporting errors etc)
- it doesn't help very much in restoring files, and just make sure that the latest backup gathers in a same folder all the files that can "just" be copied
- by default it backs up the "conventional" directories recognized by the freedesktop standards Documents, Videos, Music, Images
For instance the Documents folder is an item (and its complete backup is a "step") and so is the Videos folder, which makes it easy to display the progress of the backup step by step ("your Documents have been backed up", then "your Videos have been backed up" etc).
And this is mostly interesting because it makes it possible to define "custom" items. The basic examples, provided with the latest release, are the backups of the databases of several applications (Thunderbird, Miro etc) made by exporting their data as flat regular files in temporary folders that can then be backed up with BackupMonitor's internal rsync routine.
Of course Ubuntu's setting of DejaDup eradicates the uses for such features by backing up the full content of my home folder. However I still kinda miss the ability to add some "custom backup steps".
Anyway, and since we're at it, if you use DejaDup on Ubuntu, you may be interested in adding space consuming useless stuff like ~/.cache to the exclusion list of DejaDup ((and if we're at the same level of paranoia you'll do the same for sensible privacy related data like ~/.ssh)) !