It will have several advantages: fast to set up, solid walls for security and to lean against, quiet with no flapping canvas, easy enter/exit, dirty boots and dog on the floor, way better in storms, room to store light stuff up top. As Scott said warmer (insulated) and safe to use a small cat heater. And NO freaking zippers.
Disadvantages: maybe a bit top heavy, overhead clearance reduced, less storage room and my design will only sleep one person and a dog. I think my Christmas present this year will be a welder and some square tubing.