I've found the call quality rather mediocre. People sound kind of robotic - it's always difficult to describe, it's like similar tones are just mushed together to much. I can tell what they're saying, but I strain to do it, whereas on a good phone I don't even think about it. It gets worse if you're talking to someone else on a mobile phone.
I haven't had any background static or anything though.
I've had just as many people ask me to repeat myself when I'm talking on the Incredible as I have with other phones.
I think it won't drop the call as soon as other phones, but I think that's just that it will hold onto an unusable call longer. I haven't been impressed with the reception either, but that's also a topic for a different thread.
The volume is adequate but not exceptional either. As someone else described it, you could hear if you're in the back of a taxi cab, but if you're sitting at a table at a restaurant with people talking around you (say the person you're talking to is having trouble finding the restaurant they're trying to you at) it's not loud enough.
I was sitting in a bar/restaurant yesterday (no music, just people talking). The reception was borderline. I tried to listen to a voicemail someone left me - I could barely hear it, and there were some dropouts while listening.
I borrowed a friends phone who also had Verizon. She had a Motorola Entice W766, or at least that's what I think it was based on what it looked like. It was definitely a Motorola. With her phone, it was loud enough, the voices were easier to understand, and I didn't get any dropouts (because of reception) while listening to the message.