I have used them for plumbing and A/C. Telephone reps are very friendly and helpful. Techs are also very friendly and helpful. I think there service is excellent.
The only reason I have to give them four stars is that they made mistakes installing my A/C unit. They were very courteous and respectful of my home but they made mistakes that didn't become clear until several months after the install.
Luckily, they have come back to resolve those mistakes twice over the past 9 months. Both times, there was no charge and it was a considerable amount of work.
I did sign up for the "comfort program" where they come twice a year to service and check your unit. When they do come, they spend a couple hours checking everything. I don't think the program is any particular deal but they don't cheat you on the service.
I plan on using Donley again in the future. I'm sure they aren't the cheapest but I feel I can trust them. If they do make a mistake, they make it right.