While being spacious, the main bag fits as carry on bagage on all flight companies (including Ryanair and other low cost airlines). 
The front backpack can be removed/attached by a zipper, and is acutally a decent backpack that fits A LOT and has adjustable straps, instead of being a glorified bum bag. We also like that the bag is waterproof (and that same material remains odorless!) and has a simple design, but that is personal (des goûts et des couleurs, on ne discute pas, right?). Our own experience tells us the wheels are strong and don't chip/break from heavy use on any surface, and the zippers hold up well, even when we stuffed way too much in the bag.