I have owned about a dozen packs and cases over the years, with several made by LowePro. Generally I've found their products better designed than class-comparable items from other makers. In fact, I purchased this Whistler pack to replace a LowePro Flipside 400 AW (Mark I) which was the only LowePro item I was somewhat disappointed with. The Flipside, I feel, was designed to compete with generic packs that folks use to shuffle half a mile from their car on a well-maintained, easy trail. So a comparison between the Flipside (which has similar construction to most run-of-the-mill packs) with this rugged Whistler pack is illustrative.I usually keep most of my main gear in a large photo pack. As I am traveling further afield and in more rugged terrain, I picked up the Flipside originally as a secondary smaller pack. I repacked gear into the Flipside for day outings where I would hike substantial distances or off trail, lightening my load and carrying only what I needed. I liked that the Flipside opened on the front, as my climate can be wet and I need to be able to set the pack down, get gear out, and not wind up putting mud against my shirt afterward.Other than that, I learned that the Flipside had numerous flaws. Lunch and accessories had to go in the main compartment with gear, and I had to take care not to put anything in there that might get my camera wet or gooey. The Flipside does have an accessory area on the back, but it is thin and flat, and it gets crushed every time you set the pack down, making it barely usable. The shoulder straps were insufficiently padded. The chest strap regularly slid off completely and never stayed in place. The waist belt was insubstantial. The mesh on the side was awkward to put tripod legs into, and tore on my first off-trail adventure. The zippers were small and flimsy, and sometimes jammed on things; one zipper pull broke. And the worst was the straps: several broke on my last outing, finally killing the pack for good.The Whistler II, like the Flipside, opens up on the side against your body. Beyond that, the Whistler II looks like it was constructed as an apology for every failing of the Flipside. The Whistler II has an added compartment at the top to place lunch and accessories away from camera gear. Instead of the thin, useless back compartment there are two areas toward the back side: an interior laptop sleeve, and an outer area that is separated from the photo section by a tough waterproof material (hypalon?). The outer area is designed to hold snow shoes and similar gear, and what do you know but I just got snow shoes last winter! The main compartment zipper is the sturdiest I've seen on a photo pack and the area against your back has enhanced breathability. The shoulder straps have substantial padding. The chest strap is engineered to be adjustable on the fly, but it stays in place when you set its height. The waist belt is reasonably padded for a 2/3 curvature roughly. A tripod can be mounted firmly and quickly to the pack's side. The straps are wider and thicker than on the Flipside. Zipper pulls are comfortable to use.I should note that I specifically chose the 350 size for my Whistler II because the interior main photo compartment measurements were almost the same as the Flipside, and I didn't feel I needed more capacity (or else I would simply take the large pack). Though the sizes are numerically almost the same, the padding in the Whistler is much sturdier and stiffer. I had to rearrange gear from my Flipside configuration, and then everything snugly fit with no room to spare. But I am not complaining, because the padding actually looks like it would do a great job protecting everything when I take a spill. [Pro tip: the Whistler I 350 interior is smaller than the Whistler II 350.]My only two quibbles are: First, I'd like the shoulder straps to be adjustable at the top. LowePro calls the shoulder strap styling "aggressive," but I call it "could fit better." One size does not fit all! Second, I would like the padded portion of the waist belt to go further around my waist. I feel someone with an average waist should have 3/4 wrap of the thick part of the belt, and a thin person should be 4/5. The point is to comfortably transfer weight to the waist so it is not carried on the shoulders, and to do this a large flaring waist belt is required for packs weighing over 25 pounds.I haven't used the pack enough to tell whether the zipper pulls might be prone to failure if they catch on branches, but I'm not too worried as they're only fat finger diameter. Time will tell.In short, if you're roughing it but want to baby your gear, buy this or its larger sister. This is the toughest photo pack I've owned, and the most satisfying photo pack I've used. If you cheap out, don't be surprised if your $100 no-name pack craps out in a boulder field and you have to weave a basket of willows to carry your camera gear home. I think my earlier mistake was buying a weekender pack for something it wasn't designed for. Yes, the LowePro Whistler 350 II costs substantially more, but it's the right tool for rugged country.