I seem to be in the minority with loving the position of the power button! Why change it? My Wife's Nexus 4 has a side power button and everytime you turn the device on/off you catch the volume rocker on the opposite side and change your ringtone volume EVERY TIME! For the M8 I use my thumb to reach it, but have been told I have pretty large hands to begin with.. The LED is a million times brighter than my One X (it seems to flash brighter when you have a notification on the M8).
The black bezel is a waste, but HTC have already mentioned they couldn't change this - however I'm sure they could have added capacitative back/home/recent buttons to this bezel (Like the One X), both saving screen space (I HATE the on-screen android back/home/recent buttons) and utilising 'wasted' space on the device. As it stands the screen is pretty much the equivalent of a 4.7" screen but with a lower ppi.
I keep catching the volume button whenever I touch the device, not sure if this is the 'free' case that came with it, or the buttons themselves that sit proud of the device (the one X was perfect on this point), I keep turning the ringtone up and down inadvertently
LOVE the IR feature. Hate the camera, light metering is all over the place, exposure and ISO is all over the place and it doesn't deal with mixed light scenarios well.. I don't feel its an improvement over the One X which is a 2 year old device now.. The dual camera feature is a gimmick too imo, some of the effects are cool but flawed and software on other phones seem to simulate the effect almost as well.. The quality of the selfie cam is awesome though, nice wide angle too (wider than the rear camera). I tend to upgrade devices every 24months (I buy offline, not tethered to a contract) but I may upgrade sooner if the next HTC device has a better camera, this is a more important feature to people than HTC seem to realise.
The gestures are cool in theory but I'd like to turn off all bar the double tap - when i pick up the device my finger sometimes swipes the screen and turns it on which i dont always want.
Thank God the charging socket is at the bottom, the side charge socket on the One X was damn annoying!
All in all, love the device and the battery life (anyone who had a One X knows that that phone lives attached to a power socket).
Having had a HTC Desire -- > HTC One X --> HTC One M8 I can't leave Sense! Touchwiz feels like a UI for children in comparison!
The only other annoyance I've found so far is that i run out of space very quickly, I have a 64gb SD card but can't seem to move things like Spotify to the card, so my offline music takes up a huge amount of space on the built in 16gb
I want large amounts of internal memory and then an SD card just for movies, but it seems I need to put most of my data on an SD card with this device (The One X had no external memory card, just built in 32gb and it was fine for me - maybe a bit limited on the amount of films I could keep on the device at a time).
I've had my One M8 for just over a week now