I had a new battery for my S3 used because I realized how my old original Samsung battery ballooned. I also had a problem with the fact that my phone very quickly lost its battery life and from about 30% battery, the screen started to flicker and then ausschaltete. So had a new battery here! I can only describe my first impression, which turned out to be very positive. I no longer have it, my screen flickers problems. And the battery life is also much longer!
The reason why there are only 4 star hides the fact that the charger which is in the 2 batteries, one is a bit too loud while charging the batteries. It's not deafening, but I will not let it run while I'm sleeping, but because it is loud enough to me to make it difficult to fall asleep.
I hope I could help you in deciding if you should buy the product.
I can only recommend!