Unreliable, irritating. Rated 1 out of 5 stars
Let's follow https://addons.mozilla.org/en-US/review_guide for a review on solid ground.
# Did the add-on work as you expected it to?
No. It reported failure, still something eventually appeared in the backup directory. Third try produced more data than previous ones. But read on.
* On backup, reports some missing xpi, suggests to go to FEBE Options &gt; What to backup &gt; Ignore list. "Get List" doesn't get anything.
* On restore, a popup says "Free space :" then shows a date and time. Seriously, can we trust this for a task as critical as backup/restore ?
# What features did you like or dislike?
Overall, this extension obviously doesn't follow the KISS principle : it is complicated and therefore not as clear as it could be.
* can't find anything (sincerely)
* Saved files are stored with changed names, making manual recovery more complicated than with a plain backup
* "Personal" UI choices, e.g. showing help messages in a scrolling popup (scrolling again with a silly sound again each time) in the corner (furthermore, on some other screen than the expected one in a multi-screen setup, never experienced this with any extension before.)
* Silly sounds all the time (e.g. on each click for a help item, before/during/after backup), quickly very irritating (never experienced this with any extension before.) Can be disabled but lost among other options in "how to backup" while it is a global option.
* Generally overwhelmed with confusing options. Oh, I'm a Unix guy, I love relevant detailed control, not confusing options.
# Was it useful?
No. Overall experience invites to prefer manual backup following http://kb.mozillazine.org/Profile_backup .
# Was it easy to use?
Not really, see above. At first I could not find how to just backup now...
Anyway, this is secondary to reliability.
# Will you continue to use this add-on?
I uninstall it right now and move on to the simplest backup method : make an archive of the Firefox directory and following http://kb.mozillazine.org/Profile_backup .
Several other recent review report catastrophic failure with lost data. A backup tool is a critical component, so I even doubt "that it might have some redeeming value for a few people".
Hence, following official guidelines https://addons.mozilla.org/en-US/review_guide :
1 star: Bad. Add-on either doesn't work correctly or is utterly useless. You can't think of any significant reason why someone should give it a try and are recommending that it be avoided completely.
Moreover, extension website shows a deceptive add (disguised with fonts and colors similar to the rest of the page) to some magical registry cleaner for Windows. This does not promote trust.
Notice that the number of users of this extension is on a downward trend https://addons.mozilla.org/en-US/firefox/addon/febe/statistics/usage/?last=365