I bought 6GB variant black and it looks amazing ( looks wierd in the picture) . SD636 performs smoothly, no heating issue at all and battery backup is good ( you will feel upgrade difference from sd 625) . Front camera is brilliant and back camera is also very good. 6gb ram is an overkill and you don’t really need more than 4gb as of now. But that 2gb extra ram might come handy when the phone gets old ( useful if you don’t upgrade your phone every 1-2 year) . 4gb version is so much value for money that 6gb version feels over priced but if you compare with other phones with 6gb ram suddenly you feels the price is not that bad.