Had my HTC One X for two weeks now, and I can say the screen is certainly beautiful, but I have experienced some problems with it...
First, is that I noticed sometimes there's a kind of static flickering near the notification bar at random intervals. This happens at totally random times on the homescreen, so I am not sure of what it's caused by. It's not a real big problem, but just something I'd like to point out.
Another, this happened twice on me, during the first three days of use... I opened up Instagram's camera, and around 1/4 of the left side of the screen was covered in flickering static. I snapped a picture, and it came out normal, but when I went back to Instagram's camera, the flickering static was still there. I opened up the normal HTC Camera, and the static was still present. A simple reset of the phone fixed the problem, though. It did scare the shit out of me.
The screen has gotten better over the course of the two weeks I've owned this phone, so I'm not overly disatisfied with it, still the best looking screen I've seen on a phone yet.