The Nexus line's reputation of bad camera phones seems to have stopped at the Nexus 5, but Google isn't limiting the improvement to hardware. The Nexus 5's 4.4.1 update took what was already a much better camera and improved its launch time and focus speeds by half a second. That may not seem like much, but in photography it makes all the difference.
Image quality isn't a staggering improvement, but in some images you can notice an overall better exposure, especially for low light situations. Here is an image in a high contrast environment from the Nexus 5 pre-update:
Compared to after the update:
A noticeably brighter image shows how Google has improved shutter time in relation to metering. That being said, I still prefer the first image because it retains more information in highlights.
In this image you get a good sense of the improved shutter. The update provided a better exposed image:
The real star of 4.4.1 is the speed at which the app launches and quick focusing the camera can now do. Although there is a minor difference in image coloring/exposure, it's the actual experience of using your camera app on the Nexus that shines, especially in situations—dark bars, fast action—where you're more likely to reach for your phone to get a quick shot.
You can check out additional photos from both updates on our Flickr page for further comparison.