I've waited over a month from the time of order for these to become available, but I kept consoling myself that it was a genuine HTC product and would therefore be perfect, but it's not perfect. It is genuine HTC and It says it is for the Desire on the packaging, and it fits the screen dimensions perfectly, BUT, it has a hole in the top right corner, and a cutout in the top left, neither of which appear to be necessary for the Desire. Maybe there is something hidden under the screen that they can't cover, don't know, but a tad annoying.
EDIT: The cutout and hole appear to be necessary after all as they are for the proximity sensor and the light sensor, which apparently will not work if covered - indeed people on one forum have reported the proximity sensor has stopped working and all have in common that they applied a cover with no cutout - upon removal, the proximity sensor started working again.
Application - The piece with the cutout seems to go down fine anyway, but it annoys me to see it there when it shouldn't be, but the section with the hole just won't sit properly. I put this on with a great deal of care, and no matter what I try i cannot get that part to fit flush with no air bubble, and yet it should be easy given the hole. Again the hole itself bugs me, but I simply can't understand why it won't go down 100%.
Performance - No complaints whatsoever - Was worried that my touch screen would become less sensitive, but it works perfectly - wouldn't even know it was on there.
EDIT: Two weeks in and no problems whatsoever. The bit that wouldn't sit right around the hole appears to be the same on every review I've seen, but if you can get past that, AND get it on dead centre (use a credit card or something to flatten it as well whilst you put it on), then I think it's great. Smooth as hell, cleans easily using a microfibre cloth, and looks invisible, with no detriment to sensitivty at all.