The biggest problem I see with the Nexus 5 is the inability to focus while recording video.
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Here are more photo and video samples.
http://www.androidcentral.com/nexus-5-initial-photo-and-video-samples
This can be a founded fear for sure. If the camera is based on the G2 at all then it might be an issue. The G2 has issues with autofocus, although I have read that it might be software and flashing another camera program helps greatly, but I haven't tried this.