I'm a power user and have had nothing but trouble with Samsung Galaxy phones. The worst is the tendency to just randomly change settings. It's not accidental key presses. Things 5-6 layers deep will change themselves like converting the clock from 12 hour to 24 hour or turning off automatic time zone. Bluetooth in my car is hit and miss.
Phone" always connects but sometimes I have to reconnect to get the media audio to connect as well. And it's not just my car. even my Sharp boombox experiences this on occasion.
I thought I would give Samsung one last go-round and got a not 4. It's also a great phne but the same problems have popped up. I've done everything from clearing the bluetooth cache, the regular cache, and even a full restore just a week after I bought it. Charging is intermittent on known good charger/cable combinations, sometimes dropping to just 11%!
Bottom line is that it seems to me that Samsung is always in such a hurry to release the next best thing that they don't take the time to work out bugs. And we have to live with them for months or even a year before they get addressed. I think I'm done with Samsung. Gonna give that LG4 a try. I'm a photography buff so I have high hopes.