Although performing battery (power supplies), but does not work in my Galaxy S4 the NFC feature. Also, under the front no wires or chips, as in the original, to recognize. The supplied battery is not optically already different than the one shown in the photo (the NOM logo missing - see picture), probably that is the reason of the trouble.
As for me a functioning NFC to 80% in the evaluation flows (it need at least 3-5 times a day), I rate this product starting! At least for people who need as NFC.
For capacity and maturity, I can not say anything, battery went after a short check back!