The channeled back system here helps to keep the pack sitting snugly against your back whilst still allowing air to flow. In fact it’s not noticeably warmer than many of the mesh models, and has the added benefit of great stability.
Rear-entry zip is a joy to use, allowing easy access to deep-buried kit without having to empty your pack, whilst also being part of the compression system that really helps keep the load in place. Asymmetric side pockets give the option to zip away your water bottle or have it in a mesh pocket, albeit with the mesh pocket being a little too small to securely hold a typical Sigg bottle.