Well ... I don't know if I'd say it's very poor (especially compared to a Motorola Q).
It depends on a lot of things. How you lay/hold the phone during the call. If you lay down on a flat hard surface (like on a glass table, or cup it the right way with your hand), it'll be pretty loud. If you just hold it up 'open air', it'll be more quiet.
The other caller - some people have bad mics on their phones. Some people I have to turn my volume down with, and other people I have to turn it up. So it all depends.
Using it in a car is gonna be tough - not many things sound loud in a car/train/subway. In fact, I often have to turn my headphones up higher than I think is "good" for my ears on the subway, cause I can barely hear it otherwise! Let alone use a speakerphone.
It's not ear shatteringly loud - but I don't feel it's a piece of junk either. It's certainly louder than the first gen, at least.