This is a photo of my daughter taken with my One X. Great shot and the HTC One may take the exact same quality picture. The major difference is "pinch to zoom" or cropping. A 4mp camera would not allow this "zoom". Probably would only allow about half of what you see here.
Have you ever taken a photo and when looking at it "zoomed in" to get a better look at a necklace your subject was wearing, or to see the text on a coffee table book that was in the photo etc? You won't get as "close" with a 4mp photo.
The Average Joe smartphone pixel explanation-uploadfromtaptalk1361392141158.jpgThe Average Joe smartphone pixel explanation-uploadfromtaptalk1361392168690.jpg

From my HTC One X running ViperXL 3.2