I just did a phone changeover, so I've got info for both.
LG Viper 4G LTE --
Phone: Works
Address book: Works
Music over BT: Works
Apps: Worked at first, but then slowly started "disappearing" (graying out) and saying the app wasn't installed, even though it was. Happened to Pandora, Stitcher, and TuneIn, one by one. Uninstalling and reinstalling did not resolve.
I had some intermittent connectivity problem with the phone, which I attributed (it turns out correctly) to the phone being old and beat up.
Samsung Galaxy S4 Mini --
Phone: Works
Address book: Works
Music over BT: Works ONLY if I manually start a track in the music player first.
Apps: Stitcher and TuneIn, though installed on the phone, are grayed out and show as "not installed" by the HU. Pandora shows as installed, executes, but won't play anything.
I believe the issue with the Bluetooth music in this model has to do with the difference in players. On the Viper, the music player was a widget that was always loaded and ready to go. On the GS4 Mini, you have to actually execute an app. It's not a big deal to me; I have an Attache drive plugged into the USB port that has all my music and more, so I have no need to stream the phone's BT music. I'm a little irked that the apps aren't working, though.
Oh, and for those who had seen my posts in the MyLink thread about random disconnects or not connecting on startup, that issue seems to have gone away completely since switching to the GS4.