A leaf blower is not even half as loud as a mower.
Actually, I guess that's true. I suppose leaf blowers just irk me more because they seem so unnecessary compared to lawnmowers (in most situations here, anyway - different to what you're talking about).
I think they can be louder than lawnmowers, or perhaps it's just that I find the sound more irritating.
I've rarely seen a person wearing ear protectors when using a lawnmover, but they almost always do when using a leafblower.
I've seen a few around Ireland, so I was quite surprised that a UK ehellion has not. However, they're usually used around large parks/houses and actually, I've seen one being used at the American Embassy in Dublin
When I was visiting the US a few years ago, my hosts next door neighbour used his at 7 every.single.morning. And then at 7:30 his daughter would practice her piano, which wasn't quite as irritating, but when you only got to bed at 1am... ugh.
I suppose they're handier than a rake for gathering them together, but as PP pointed out, you usually still have to pick them up at the end.