You may have already bought a GH, but I thought I'd weigh in with my review anyway. I bought a Sunglo lean-to model 1500D about 16 months ago. It was one of the few models I could find that was less than 6 feet wide (5.5' x 12.5'), and I think the price was good given that you get nearly everything you need in the kit. Overall, I'm quite pleased with it. Installation was fairly easy, although the instructions were not entirely clear in all cases. I called Sunglo a few times during installation, and they were able to answer all my questions. I had a few missing or incorrect parts in my kit, and they sent me replacements without much delay. It took me about 3-4 days to assemble the greenhouse, and at least that long to prepare the foundation and wall it would be mounted to.
The Sunglo GH is quite sturdy, and has held up well in wind (60+ mph gusts), heavy rain, and 6" of snow. The active exhaust fan and vent work quite well, although the thermostat is off by about 15 degrees (e.g., I have to set it to 30 to turn the heater on at 45 degrees). The benches are sturdy, and I can put some very heavy planters on them. I can easily remove one or more panels from the bench to grow taller plants -- I started my tomato plants about 6 weeks early and they were nearly 4 feet tall when I moved them outside in May. It's a bit tight inside, but it's the largest GH I had room for. Mine is installed on top of an elevated deck (to catch enough sun over the roof of my neighbor's house).
If you have any other questions, I'd be happy to answer.
Thanks vitaveggieman for the review. I did end up buying a greenhouse from a different manufacturer, but I am sure your review will be appreciated by others weighing options. Even though I ended up going a different route, I think the sunglo models do have a lot to offer. It is SO nice to walk into my greenhouse and pick peppers, tomatoes and see flowers when there is snow on the ground. This is the first winter I've had it so the heating bill is being closely watched. I may have to forgo heating it in the coldest 3 months next winter if the cost is too high. But a heating bill is cheaper than a trip to Hawaii!