So I had a full day to use my new nexus 5 and I am loving it so far. Using this and my One side by side, I would say that battery life is about the same on both devices. This device is so snappy its unreal but honestly when I go back to the One it feels just as snappy to me so maybe all this talk about high end specs can finally be put to rest.
As far as camera, honestly I think the One owns the nexus 5 in every conceivable category, in my opinion its not even close. I probably took 200 pics/videos today using both devices and to me the One just beats it. Speakers are great for what they are but this is something else that the One is far better at as well. I also think that the One still has the best screen thats out right now.
As for 4.4 kitkat, I love the google integration, it makes everything so simple and easy to use and easy to get to but what most important to me though is rf performance. Now when it comes to 1x/3g/lte it straight up kills my One. The rf differences between both devices on 1x/3g aren't that significant to complain about but the difference between lte is ridiculous. My nexus was easily averaging 10 to 15dbm's better than my One in every situation I could put both devices in, it was shocking to see in all honesty and to be quite frank I am totally impressed. The rf performance alone is worth the $350 price tag.