Excellent. He was very prompt, earlier than estimated time, and called before coming. He was consistently courteous, polite, respectful, and professional. Most outstanding, and most important to me, was his work ethic. I believe he took the same care to do it right that he would have with a member of his own family, and for this reason I will call Duncan again the next time I need the services of a plumber. The prior hot water heater installation from the prior owner had a few oddities/complications and safety concerns (some of which I suspected of ahead of time); a contractor with less concern for quality than Duncan might have just done a standard installation, leaving the rest of the issues alone, which would have left me with safety risks. I was impressed that he wanted to do it right and to make sure that safety was optimized. The leaky pipe situation was also a bit more complicated than usual, due to nonstandard pipe sizes. He knew that cost was a concern for me, and any time additional costs beyond the phone estimate would be incurred, he informed me first and asked whether I wanted to do the additional work at this time (I did), rather than assuming or adding costs without my agreement (the estimate was made by phone without knowledge of my plumbing oddities - I had not been thinking of the oddities when asking for an estimate when my old hot water heater failed). He also had to rearrange his work schedule that afternoon because of the complicated nature of the work needed in my basement; I was also impressed that he did that (another plumber might have just said he'd have to come back another day, which would have caused me inconvenience and more cost). Given the amount of additional work needed due to the plumbing odditites from prior owners, the cost was actually less than I had feared it might be. I also felt that his charge for time/labor was very reasonable (he could have added additional time/overtime, but did not). For me, this experience with Duncan took the fear out of calling a plumber (which to me is high praise indeed). They were recommended to me by word of mouth, and similarly I recommend them without reservation to anyone in need of plumbing services, based on my experience with this plumber.