I like my greenhouse. It's small, passive, built into a hill for additional thermal mass. It has a door on either side in the direction of the prevailing winds so on the hottest days it's seldom more than 5 degrees above the outside temperature. The roof actually faces north, so even in the summer the sun doesn't hit it directly. During the winter the sun hits the front wall straight on. In five (?) years of measuring it has never gotten below 20 f and only reached 20 when the outside temperature was in the single digits.
The first frost date (barring any unseasonal freeze, like last year when it hit the teens in September and I wasn't expecting it so the doors were still open) is the end of November. It's never frozen inside after March 1st. It does freeze a couple times a year, but that's a design flaw I think. I designed it myself, for the location. An eco system is gradually developing, making pest control a non-issue.
I have learned a lot in the building and use, so any future greenhouse would apply those lessons. If I got the chance to move to a larger place I would certainly be building another--site specific, and entirely passive. The glashaus to collect heat works well in the far north, or areas where it seldom gets above 60 degrees. Anywhere else it has to be modified for the location.
The "suck factor" isn't greenhouses as such--it's the cookie-cutter greenhouse designed for cold climates and aristocratic playtime. If you went into a desert property and tried to force it to grow tropical fruit without adjustment, would you blame the property for your failure? A greenhouse is no different.
Zone 5b/6a, alkaline soil, 12 inches of water per year. For now the goal is a water independent urban homestead with edible landscaping and food forest.