I am posting this review after about a month of daily use. I will update the review after some time has passed or if my opinion of this product should change.For starters the quality of the pack is top notch. You can tell great care has been exercised to ensure quality materials and workmanship. Seams are heavy duty and well reinforced and the materials are thick and durable. Zippers are also of high quality and open and close without hanging up or getting the pack material caught in them. The layout of the pockets is superb and the pack has a nice low profile that hugs the dog and adds very little bulk. The straps are a little tricky to get the hang of and will require some tinkering to get them set just right but once set, they remain snug and secure. The water bladders have been great for me so far, I have not had issues with leaks or any of the other problems I saw reported in the reviews.This pack is for my 70lb German Shepherd and it fits her quite nicely (I purchased the large model). As I said getting it set for her size was a little tricky and I have had to readjust a few times but overall I am happy with how it fits her. It does not seem to impede her movement or chafe her in any way, although I will admit it would be difficult to know for sure if she were uncomfortable. I will say one odd thing I have noticed is that toward the end of our walk (about 1.2 miles each trip) for the last few blocks she really seems to drag and I almost have to pull her to get her to come. I have never had this issue with her before the pack and it has made me wonder if she is simply tiring quicker from the extra weight (not likely from a younger, healthy high energy dog) or because the pack is somehow uncomfortable by that point in the trip. It may also be that she is still getting used to it. For reference she only carries the two bladders, typically half to completely full, so it isn't that much extra weight.I will say her behavior has been modified by the addition of the pack to our daily walks. She is generally a well behaved dog but I did have issues with her pulling before we got the pack. The change has been amazing. When she has it on she tends to stay right by my side and walk and a smooth even pace, mostly ignoring distractions. The additional work seems to help her focus and give her something to keep her from getting sidetracked. This was a primary motivation behind the purchase so I am very happy with that aspect.I will say this, if you are looking to get your dog a pack that will last and likely be the most comfortable choice for him or her, look no further. I think the quality of this product is undisputed. The only question is, how will your pet take to it?