It has 2 speakers, on top and on bottom, which make it ideal for watching movies or playing music without headphones. It has also Dre Beats built in.
It has a feature called BlinkFeed which annoys people, because they can’t get rid of it (they can only hide it).
It is made of a uni-body aluminum design, so it feels premium in the hand (unlike cheap plastic feeling phones).
Pro or Con
This one depends on who you ask, but some people say that the Uni-body aluminum draws heat away from the processor to prevent overheating. I however, don’t think this is the case. I think that the uni-body design actually prevents heat from escaping, and causes the device to overheat. There are already numerous reports online of users complaining that their HTC One is overheating.