Batteries and stuff.
I have had the M8 for a week now, and apart from the first day where I hammered the phone HARD, I haven't gone to bed with less than 50% charge yet. Last night was 64%. I am a moderate to heavy user and I'm getting (extrapolated) roughly 6 hours of screen-on time out of this phone. I get up at 7am and retire at midnight. Trust me the need for additional ergs is going to be unbelievably rare on this phone. And if the battery packs up and goes home before the first 2 years is up, HTC will replace it under warranty for free.
As to photography: photography is about emotion and moments, not f-stops and pixel counts. This camera is sweet as - its "only" four million pixels deliver fantastic image quality, colour accuracy and light accuracy - and it is more than adequate to the needs of the millions of people who will buy this phone.