So, I felt I had to chime in on this one, instead of sitting on the sideline and watching. I bought the One the day it came out and came from an IP5 and I could not be happier. I actually have a N5 on order, to be delivered Nov. 21. I love the google experience, hence my purchase, but it has to overcome a pretty hefty challenger or else its my sons.
Here are my impressions of the One;
I liked Sense, but I love love my GPe 4.3 ROM with pieces of KitKat. I can't express how much I like the ROM I'm running. Swipe to on/off, popup notifications, volume on, power management, I can go on and on, but I have to say with every update I'm amazed there can be any improvements.
I get all day battery use with moderate to heavy use. The screen is sharp and crisp. I run viper4android and that makes the sound that comes out of the speakers very very good. I mean when tweaked, it sounds like a decent mid level setup. I've been into audio for 40+ years and have an excellent home system. While not quite in that league, this holds its own. I mean I get honest separation via the 2 speakers and with some features of v4a, it sounds excellent. I'm not sure the N5 can match the audio, but again its all your requirements.
Camera is decent, I've caught some nice shots, nothing to beat a slr, but i've been happy with it. I've not been disappointed by a shot and said to myselve, oh man this shot sucks.
I do have a case on mine and would on a N5, thats just me. However it does not really take away from enjoying the build quality.
After all this you may say, so why you get a N5? Well, I like the google world abhor carrier bloat and like what the N5 has in terms of hardware and software. I will try it for a few weeks, just pull out my sim and drop it in. I will root it of course, I like some root features, but will not flash a ROM, that would be insane.