Pluses: It wasn't expensive. It was easy to put together. It can be taken down and stored for next year. The door and windows are easy to use. It's got a lot of space. It got warm fast! The cover is reinforced plastic and seems to be really tough.
Minuses: the frame is very cheap metal pieces that will probably not last beyond one or two years. It's light--we nearly did a Mary Poppins when the wind caught the cover. It was all I could do to hold it in place while Larry hauled cinderblocks to weight it down. Definitely needs tie-downs or some sort of anchor unless you want a big green kite. I'm still a little worried about it in high winds.
Overall, I think it might work very well. We kept the assembly diagram because we can make the frame ourselves out of plastic plumbing pipe and re-use the plastic cover if the metal frame dies.
We will heat it this year with either a kerosene heater or an electric heater. Larry made some shelves with block and boards so it's ready for my little seedlings. That will be next weekend's project, I hope.