I had them come out for annual maintenance on my furnace and to check out a couple minor annoyances I had with my HVAC. They gave a 2 hour time window for their service call, they actually arrived within the first 15 minutes of the window and called me 10 minutes before they arrived to confirm they were on the way - I must have been his first stop for the day.
Service technician was courteous, friendly, knowledgeable and very helpful.
Service pricing was reasonable.
Their website and their people give the impression (and rightly so) that they really care about their customers.