The first thing you feel with the Tree Runners is how light and airy they are. On a 105°F (40°C) day exploring city markets, the difference between this and a standard leather or synthetic sneaker is night and day. Your feet feel noticeably cooler and less sweaty. It feels like you're barely wearing shoes at all, which is a blessing in oppressive heat. The downside of all that airflow? Zero support for your feet. The comfort is unstructured, on par with a basic pair of canvas sneakers. Travelers with any foot issues or those planning on trekking more than 4-5 miles a day will likely find them inadequate. The biggest worry I hear from travelers is about its performance on wet surfaces. The outsole offers very little grip, and many people have warned about dangerous slips on wet cobblestones, tile, or even smooth pavement, a critical safety issue you can't ignore.