Apps do automatically go to sd when the app allows it on my s3 however only to the internal sd which is now about 16gb. The problem is that you can't send them to the external usb which you could before Samsung set up this new internal sd feature.
Before you had phone memory and external sd but now you have phone memory and internal sd plus external sd. I am sure for the average user this will never be a problem but for heavy gamers and people who like to have hundreds of apps it will be. Very short sighted of samsung in a phone designed for humans.
You can of course move other types of files
such as music and videos to the external card but have not found whether or not you can move default locations such as gallery to it. Shoddy design which I suspect is aimed at selling phones with larger internal capacity. Seems like the have copied at least one feature from apple unfortunately a BAD one