review is for the medium size.obviously, what you need in a "day bag" depends on what you plan on doing that day. but this bag offers a good value proposition for a certain set of use cases. photo depicts a small haul from the farmer's market that i took on bicycle. lower center of gravity, and unimpeded airflow over my back, are both big pluses on a bike.carrying loads on your hips will always be more comfortable than on your shoulders. and traditional backpacks in the 10L range mostly come with pretty flimsy hip belts, often no more than bare webbing. this belt is wide and mildly padded, and comfortable enough to really cinch down to fully support the load."but with 10L capacity, how much load could you possibly even carry? why not just a traditional backpack?" a few reasons. a prosumer camera, insulated water bottle, keys, phone, and a snack, for example, will tip the scales pretty quickly. then there's general comfort; mitigating back-swamp; and ease of gear access. secure the pack on your rear, and sling the shoulder strap diagonally across your chest. need something in a hurry? undo the buckle, swing the bag to your front, access your gear. then swing the bag rearwards and resecure the belt. the bag has never left your person, and is far easier to manipulate than a backpack, especially when wearing multiple layers up top. i'm not currently, nor aspiring to be, an endurance athlete, so i don't value "hydration pack compatibility" very highly. if i'm thirsty, odds are i won't mind also taking 5.if you're just taking a short jaunt, the bag can be carried like a normal shoulder bag with the waist belt tucked away.why not 5 stars?firstly, style. this bag is advertised as a range bag. i'm sure it's adequate in that capacity, and maybe i will use it as such in the future. but stylistically, this thing is the epitome of tacti-cosplay. that may be a plus or minus for you. the most discreetly-styled competitor with a near-identical feature set is the mountain hardwear, costing several times as much, so the choice was pretty clear for me.secondly, the multitude of zips and webbing can be a bit much. this bag is designed as if you're going to need to lash on like 10 extra pounds of gear to it. if you think that's going to be a recurring need, this is not the right size or style of pack for you. i immediately ditched the top elastic tie-down, and will probably change the color of the main zipper pulls for ease of identification. depending on how you've oriented the dual-zips of the various compartments, the zipper pulls become a veritable rat's nest (second photo). compartments = good. not being able to differentiate them easily = not so good.lastly, reliability is, as yet, unknown. it was my sole carry-on for a recent international flight, and it was used every day of an 8-day itinerary. it basically still looks brand new. all stitching in high-wear points still looks intact, and zippers have not ever snagged. but time will tell.