Here are the cons in my view, in decreasing order of importance:
Exynos instead of Qualcomm's 810, which means most likely no quality custom ROMs
no exchangeable battery
no SD card, hence be extra careful with them factory res...
Delete all your apps (especially google apps) which u don't need. Turn off account sync, this is what the most battery drains. If u are in uncovered area, turn flight mode on, steadily searching for net could cause battery drain too.
I'm using winamp. Not bad.
I've found this in an other topic:
Switching between 3G and H is a feature of CM. It saves on battery as a 4G signal uses up more juice than 3G. You automatically switch to H when you need a faster connection but then will change back to 3G when y...
Matr1x is one of them which supports OTG.