I used it to transfer my photos and such, but I don't think I used it for apps, since I used it later. I don't know what put the apps on my phone, but it listed all the apps in my Google account and allowed me to select which ones I wanted to install, then it downloaded and installed them. It was part of the phone setup. I wasn't connected to my S3 at the time (I was charging the S7 Edge via wired charger).
I didn't transfer my music via the app because I wanted to be sure that wouldn't mess up future use of the iSyncr app as well as add more music and playlists, plus add them directly to my SD card.