So just another update:
As some of you know the first HTC One I received on 15th March had excellent battery life but the mic's didn't work and external speakers made 'popping' sounds while playing video. I exchanged it for a black One 1st week of April but noticed that the battery was struggling and would only last around 8-12 hours with normal use despite having battery saver on.
I exchanged it for another black One 4 days ago and am glad to say that this phone has the awesome battery performance of the first One I had.
Currently I'm sitting 33 hours with 7.5 hours screen on and battery level is at 34%, auto brightness and power saver off. I did try with auto saver on but to be honest I haven't noticed any significant improvement and I don't really see how I could expect to squeeze more out of it aside from just not using it.
I've noticed quite a few people wanting the black One but upon playing with the store dummy models and noticing the finger prints all over it, have decided against the black. Just remember the dummy model and actual retail unit are different. Cheap material and painted dummy phones do show finger prints especially when people just came from shoving their faces at Mcdonalds or KFC and don't wash their hands.
The retail black unit is anodised and does not show finger prints as easily as expected and can definitely confirm that it doesn't scratch easily as I stupidly put my phone in my pocket with some coins, when I arrived home and removed the phone from my pocket I was horrified at what looked like scuffs and scratches but actually wiped off straight away.