XDA User unclefab has tried and successfully ported this app into JB devices and found working smoothly. Features of Google Camera App :-
Photo Spheres for immersive 360º viewsLens Blur mode for SLR-like photos with shallow depth of fieldPanorama mode with high resolution100% viewfinder for getting the maximum resolution from the sensor (no dropped pixels)Updated UI that gets out of your way and is centered on an extra large capture buttonWorks on phones and tablets running Android 4.4+ KitKat
Downloading Links :- For Android 4.4 KitKat Devices :- For Android Jelly bean Devices :- Just download the apk file from above link and install it on your JB Device. If you face any problem then please comment.