Good day all,
I have a 4S that had 5+G of "other" that I was trying to free up. I searched and searched, tried all the suggestions and had no success. I tried a full restore and freed up the memory but didn't want to loose all my settings, app folders, etc. After a process of elimination the solution that worked for me was to delete txt messages! When I went from the 3G to the 4S I restored from a back up. I've never delete any of my txt message history... so all that information, photos, videos, etc were being caried from one device to the other for like 3 years!
I started with a test. Pluged in my 4S, synced it. Registered 5.2GB of "other". I ejected the phone from itunes. I deleted my wifes txt message (with whom I txt the most). I plugged back in and "other" dropped down by an entire Gig!! So, I tried again with another that I txt often... and sure enough when down another Gig.
So, I decided to take the plug and start off fresh... I deleted ALL of my txt messages and my "other" memory went down to .52gigs!
This is why a FULL restore has been successful for those trying to clear out "other" memory. When you initiate a Full restore, you are cleaning out your entire memory of txt messages which includes large files of photos and videos!
So this is what worked for me folks! I hope it helps someone!