The Desert Fox in my opinion is above average in quality. I haven't had many issues at all from the time I bought it until now - at least major issues. There are always going to be little things here and there that need to be addressed.
When I bought mine I opted for the dual-pane windows for the extra insulation as well as the upgraded furnace. I shouldn't have spent the money on the furnace though as it's absolute junk (note Northwood doesn't make the appliances like your homebuilder didn't make your fridge) It still works very well in the cold weather. Often times I camp in the mountains around 4k-5k elevation and during the spring and fall the temps get below freezing - heater may come on once or so during the night. Even with leaving the furnace set around 65-68 I still wake up with 3/4 battery remaining which is nice.
Anyways - the DFox has very very good insulation and is built on their custom chassis which is independently certified by a 3rd party for QA. With the DFOX you get a lot of ground clearance, heavier duty axles (I have 2 7k axles) shock absorbers and load distributing suspension etc... It's a tough beast and for as long as it is I can get into some really gnarly Forest Service camp spots (not campgrounds - but the unmaintained spots) which usually consist of traversing some rough terrain to get into. I can't say enough GOOD stuff about that aspect of Northwood and the Desert Fox.
My only gripes though would be - it's heavy (dry weight almost 9k - loaded around 13K with full water, toys etc.. Also they don't offer a slide, instead I think it offers the highest CCC of any of the bumper pull THs I've seen coming in close to 5k.
There are tons of features included like a TV (although horribly placed in my opinion) solar, fuel station, air compressor, pressure washer (runs off it's own higher power pump - but nothing like a home system) and it goes on and on.
Overall I am happy with it and it serves my family well. Maybe that will give you some insight on
