mobile

So yesterday I bought a 2.0 charger off of amazon with the choe brand name. According to the ad it works with nearly every android phone, including the HTC one m8. For the past year I have been using a charger from my last phone which was a crappy flip phone and thought nothing of it, but I am wondering does this charger truly work?? According to app "Ampere" it is much slower. Also, I've read reports about phones heating up and that's what mine did last night, is that normal? How long should it take for me to full charge my HTC one m8?