http://forums.windowscentral.com/lu...-camera-comparison-touch-response-tested.html
I have two versions of the 640 LTE at the moment, a matte black version, and a bright orange glossy version. The matte version is the same slippy plastic that's used on the 630/635 matte covers, it doesn't feel particularly high end (not that it's meant to), and the lack of a soft touch coating (see Lumia 520, Moto E) is disappointing. The glossy cover on the other hand feels much nicer in my hand, it uses the same translucent band around the outer edge as was used on the glossy covers for the 635 (similar to the dual colour covers from the Lumia 620).
This means the glossy covers are actually slightly larger than the matte covers (about 1-2mm wider and taller). The slight increase in size isn't noticeable in the hand, but it might cause issues when buying a fitted case. It depends on whether the manufacturers have used the matte or glossy covers when designing their cases.