SEVERAL BUGS! Rated 5 out of 5 stars

When I did a first backup (Full profile) (FEBE, Perform backup), it dit it (previously I had selected various options for the backup). So the first backup had a particular size (126 MB for mine). Then, a few seconds after the first backup, I did a new second backup and the size of it is completely different (6 MB)!!!! Basically, the addon does not seem to have saved fully the second backup!!! There is something very wrong with your addon!
BUT...
What I noticed later on is that the second backed up over time. In other words, I did the full backup the second time but it was not done right away, it showed the page indicating that the backup had been done but it was not yet done fully!! And that is where the problem, the BUG is. Sometimes, it does the full backup later on BUT sometimes it does NOT!!

I do have around 90 tabs opened and quite a few addons but I also have a quad core Intel processor and 8 GB of RAM!! So, there should not be any problems doing the backup.

More, all the plugins (Tools, Addons, Plugins tab at the left) are not part of the full profile. In my test, only one plugin was backed up but I have more than 10 plugins listed that were not backed up.

In summary:
1) a great addon but it must be 100% reliable when you do a backup (full profile or else).
2) More, I believe the full list of plugins should also be backed up if it is possible (not sure on this matter if it is possible with your addon to accomplish this second point).

Many thanks to the developer for this addon.

Backups are asynchronous by default

Backups are run in the background by default. Because of this, you may get the Backup Results Report before the backup is actually completed. You can change this behavior by un-checking "Run asynchronously" in FEBE options > How to backup.

IT DOES NOT COMPLETE THE BACKUP!!! Rated 1 out of 5 stars

Your addon does not work with FF6.0 and with recently installed FF7.0.
It never ends!! And even after 30 min waiting for the backup to finish, it still displays the ridiculous windows:
---------------
Firefox Envirnoment Backup Extension
Version: 7.0.2
Backup type: Selective
FreeDownloadManagerplugin(1.3.4).xpi
This window will close when backup is complete.
Note: Firefox may be unresponsive during backup.
---------------
Again, it seems stuck at this particular addon FreeDownloadManagerplugin(1.3.4).xpi and it never completes the backup process even after waiting more than 30 min!!!
The only addons saved when it starts the backup process are 3 addons (plus the one above that is not saved completely I assume).

This review is for a previous version of the add-on (7.0.2). 

Please use support forum

In particular, see http://www.customsoftwareconsult.com/phpBB2/viewtopic.php?f=5&t=1722

From reading your reviews of other add-ons, I can tell you are the type of user that thinks this is the place to ask about support issues. It is not. When you write a review, you are shown the following message:

"Please do not post bug reports in reviews. We do not make your email address available to add-on developers and they may need to contact you to help resolve your issue. See the support section to find out where to get assistance for this add-on.."

I think you will find that developers are generally very responsive to questions and/or problems when they are presented in the proper venue.