I know, it's really irritating. One thing about Nokia phones is that first and foremost they should be good PHONES. In my view the low volume of the ring (and vibration) on the N9 breaks that rule. It makes it a bad phone. I miss calls and messages regularly because of this.

One consolation is that as far as we know, the speaker itself is capable of higher volumes, but the ringer is set artificially low. There may be a settings somewhere that can increase it, at the risk of it sounding 'vibration-y'. Also a firmware update may improve things, we have to see.