Only small contact photos since iOS 6 facebook integration Before I've upgraded to iOS 6 I did my facebook contact synchronization with an app called "phone+". It synchronized all my contact pictures (and some other things as well). The photos were in large scale. So if somebody called me, his/her picture would be shown on the whole phone screen.

After upgrading to iOS 6 I switched to the integrated facebook synchronization. Now the newly synchronized pictures are in small scale. So if somebody is calling me, his/her picture will only appear in "thumbnail size" at the right-hand side of the name, but not on the whole iPhone screen anymore.

Does anybody know how to get the bigger pictures back using the integrated solution, or is synchronizing in "thumbnail size" actually the solution Apple designed?

(Additional: Maybe one with facebook integration turned on can tell me in a comment how his/her pictures are shown?)
Currently, no.
That is the way it works in iOS 6 (if you ask me, it's a better way).
But...
This month, there should be a massive redesign with iOS 7 - maybe this design will be improved/changed.