Jul came out, walked through the house with me to count the number of vents, gave me a clear quote (consistent with what I had gotten via email), and then started working from the attic down to the basement.

He did a very thorough job cleaning all of the ducts, took photos (which he let me get a copy of), and pointed out one or two places where the ducting was problematic and would need repairs.

Jul is quite talkative, but this meant he was willing to explain what he was doing, what some of the issues are that he has seen, and give some ideas on how to resolve some of them.

All in all, I would highly recommend DuctWorks and Jul - this was well worth it. I would recommend asking for the pictures - they really are worth a thousand words (dollars? :D).