Size and function are the best features in udg bags. Materials are good and durable as well, even though they have some lacks.
The sling of the slingbag is not so long-living, the leathery part starts to get cracked/ peeling off in about one year (even though I have used it only on the lighter version, the one without wheels).
The wheels are not really suited for northern climate, as here roads and pavements get covered in small gravel for safety during wintertime (when streets are otherwise covered in snow), small pieces get stuck in the wheels thus reducing their lifespan.
At any rate one of the best bags around, surely the best style.