If the vibration makes a loud sound it completely defeats the purpose of vibration as the phone is NO longer on Silent mode and highly likely its bothering other people around you. [@ Meetings, seminars etc] I put my phone on vibration for the sole purpose not to be the disturbing one.
Fair enough. But if I'm in a "quiet" meeting/seminar then I prefer just having the phone on silent mode and outside my pocket, so if the screen comes up I know there's something going on. It will disturb others as much as someone trying to get his phone (and a big one!) out of his pocket.
When someone had the brilliant idea of the vibration function a few years ago, I'm pretty sure it was meant to be used on noisy environments where you can't hear the phone, so in this case you would feel it. And for this purpose the Lumia 920 is a champ.
But once again I also do not think it's a nice sound, it sounds and feels harsh, but as long as it's not affecting anything else than I'm happy with it. That's a minor detail I can easily live with. If it does affect, then I'm sure Nokia will exchange it and in this case I'll probably get a brand new, scratch-free, freshly baked phone after a few weeks.
If someone isn't happy with it... then go for the HTC 8X, it's also a really good phone and apparently it has a smooth, lovely, orgasm-giving vibration.