640 and 640xl tries to put as much wow as they can in a low to midrange device. They have to cut corners somewhere, or it wouldn't be a low to midrange device. Personally, I want a Snapdragon 810 6" 2550 x 1440 display with all possible sensors, fingerprint reader, 12,000mAh battery all in a package that is only .5mm thick in a beautiful brushed stainless steel body with 10 karat gold edges, and I want it all for $99. Yeah, I have to give up something (a lot of somethings) to get it for $99.