Yes I had this issue also when I decided to sync my iPhone after the ios 7.03 update and I ended up with 30GB of Other! I sorted the issue by the following:
1) I did a soft reset on the iPhone using by holding the Sleep and he Home button (Not sure this actually was important or not but I did it so I list it)
2) Plugged the iPhone into my laptop
3) When iTunes connected with the phone I looked at the 'Info' in iTunes and seen it was still showing 30Gb of 'Other'
4) Tried to 'sync' just in case
5) While sync was running I selected through the category tabs for the iPhone content
6) I went to the 'Info' tab again and seen that the 30Gb of 'Other' was now just under 1Gb
The phone then synced properly.
I am not sure if this was luck, I doubt it was the soft reset but maybe an iTunes and iOS7 issue but in all honesty I have no idea except that this worked for me, shame it wasn't as easy to pop back to OS6 ;-)
HTH