The few games I have played with them I find them meh. They are mostly just a time sink and I know people in WOW that only do things for them. Thats ok if you find them fun and enjoyable, but id rather just play my games than have people shout out hey we doing the achievments everytime I go to do something. I have many myself and do not mind helping out, but it gets really old really fast.
It measures nothing other than how much free time you have and in some cases money. They dont really bother me, but they add almost nothing for me