What I did was :
1. Make sure I was on itunes 10..6.3.25
2. Dowloaded 5.1.1 from the link
3. Connected my phone to itunes
4. Held the shift key down and then pressed 'update'
5. Found the 5.1.1 download and clicked open.
6. Then let it do its work.
7. I then had to restore my phone from the back up I made before I upgraded to 6. It offered icloud or computer and I chose computer.
8. just let it run - it then asked me for a new passcode and then went on to download all my apps/music/photos etc.
I am now back with google maps working as well as youtube. Everything is as it was
Hope this helps but don't blame me if you have problems - maybe I have been lucky.