Thanks, guys. That's all very reassuring feedback. The Nexus 5 is actually for my wife, who already has a Nexus 7 tablet. She is keen to ensure that the Nexus 5 camera is capable of taking good snapshots and decent video. We are both of the view that any phone camera cannot match a dedicated compact or DSLR, largely because of the limitations of the optics.
We are familiar with the loudspeaker problem. I assume that was the same problem that affected the Nexus 7 - the buzzing sound. My wife had to return hers for repair and now the problem is fixed.