iOS 7 upgrade - how much space will I get back?
You'll get back all but about 60 MB of space. (Which is about the same space as all four movements of Shostakovich's Symphony No. 5 take up when copied to my iPhone.)

On my 32 GB iPhone 5, I now have 27.94 GB free space under iOS 7.0.6 instead of 28.00 GB that I had on iOS 6.