The HTC One has ultrapixels, not megapixels. Ultrapixels are larger than megapixels, but unfortunately, they only exist inside HTC’s mind. HTC made up the word and then used it to describe their new phone. It’s unfortunate that they need to go to this length, but perhaps it is for the better. After all, in most cases, the maniacal focus on megapixels has led only to more mexgapixels, not to better photos.
Technically, the 4-megapixel HTC One has enough pixels to produce a high quality photo, and larger pixels will capture more light. Maybe now camera manufacturers will talk about image quality, rather than who has more megapixels. See More than megapixels and Will the megapixel wars ever end? for more on this subject.