In terms of engineering this phone isn't perfect. Front facing camera is unusable, charging pins oxidize really quick and become useless. On the other hand, it has the best materials ever made. Seriously, I never used any screen protectors, never used any bumpers or cases, my phone is always naked somewhere in the same pocket with my keys and loose change. Despite any logical assumptions, my One X is as good as new. If you look very closely, you might notice that it became rather glossy on the back with a bit of small scratches consecrated on a small area where the housing touches the surface. Also, my battery degraded so badly, it gets from 100 to 0 in 8-9 hours of a little to no use.
But other than that, this phone is a masterpiece. I have my old E3D laying around, I've had it just for one year (I have HOX for almost two years already), and it is absolutely destroyed.
And you know what? Looking at current HTC lineup, I'm not going to replace it till it becomes fatally unusable. Best phone ever made.