RESTORE NOT NEEDED TO RESOLVE "OTHER" SPACE ISSUES
I may have a solution for this as I also experience this problem on the iPad 4 (retina display) 16gb where by I had over 2gb as "other space"
First and foremost "other space" should be between 800mb and 900mb - these are preferences, apps, syncing data (not the actual photos your contacts yo may sync)
I plugged my iPad into computer and did my normal sync
I ejected the iPad.
I turned the iPad off by pressing the on/off button and then sliding across to power down
I waited 5 - 10 minutes
I turned the iPad back on and waited another 5 - 10 minutes
I connected it back to my PC and opened iTunes
I noticed that the 2.74gb "other" space reduced to 835.4mb within a few seconds.
I downloaed iExplorer and installed it (free version will do the trick)
Have iTunes open with iPad already connected
Open iExplorer and click "demo"
Under your iPad navigate to Media> Photodata> Thumbnails
Here you will see the following file names: 158x158, 240x240, and 332x332 with the extension .ithmb - make a note of these file sizes.
Right-click each one and hit delete and click ok if a warning sign comes up
Eject iPad using iTunes
Close any open apps
Do a hard reboot - hold the home button down and the on/off button together until the screen goes black and turns off - this can take up to 10-15 seconds to do
Sometimes the iPad may reboot by itself, and sometimes it may not - if it doesn't use the on/off switch to turn it on.
Open iTunes and then iExplorer and navigate to Media> Photodata> Thumbnails once again
You will see the same files you just deleted - but instead of being the size you made a note of, they will be considerably smaller.
Go to iTunes and check your "other" space and should be within the 800mb to 900mb
This also works with the iPhone 4s and other devices running iOs 4 onwards.
I have several devices currently on iOs 6.1.1 and all the "other" space currently shows between 800mb and 900mb which would appear to be normal
I hope all this helps and please let me know if it solves or doesn't solve your issues
RESTORE NOT NEEDED TO RESOLVE "OTHER" SPACE ISSUES