I reckon a lot of the comfort/shin-bang hype is because of the leg fit. The fit in the foot area is much of a muchness with any other boot. Where they differ is that the leg, particularly the cuff, is very narrow compared to any other boot. So if you have chicken legs they're awesome and probably one of the few boots that will fit you comfortably and not give you massive shin-bang because your lower leg is slopping around heaps, despite the foot fitting perfectly.
All part of the reason you should go to a shop/bootfitter and try a whole lot on.
Full Tilts fit my foot pretty nicely but within a minute or 2 I knew they would be agony on my calves. So I'm steering clear.