If you want a short answer on whether you should buy it or not, simple answer is yes. However only if youre on a budget and you need a big rucksack.
Lets start by pointing out that this rucksack has an important feature, top stabilisation straps. They connect from the shoulder straps to the rucksack. They help to bring the bag closer to your body if you carry a heavy load.
I went with this bag for an hour long run with a 20kg plate inside. It surprisingly held up to the test. The compartments are fairly big and the bag is somewhat comfortable (with 20kg inside).
I did mention so far that the bag is really good so why did I rate it a 4/5? The stitching in some areas is very flimsy and minimal. The hip belt has extremely small padding section even for me, I have a really small in the waist. Because of this you can really feel the 20kg and I would not advise on putting much more inside it.
Few things to note with this rucksack before buying. When fully packed and extended to 85l the top cover is a little too small. However there is an additional cover inside which can be tightened with the shockcord. The molle/PAL on the bag is not the standard dimensions so some molle gear might not fit. The bag is not waterproof! Just like the seller mentioned its water resistant and if you live in the UK like me then you might want invest in a waterproofing spray.
Excellent quality bag with a huge main compartment. You wouldn't even notice that I have an entire tent stashed away inside it. Main thing that bugs me is that the carry handle is just a small single loop of nylon strap when smaller bags have a folded over, double stitched handle that is far easier to carry it by. So it isn't really very easy to pick up off the ground without also grabbing the top flap at the front of the bag.
The waterproof drawstring cover around the top won't close fully if you load the bag up to the top or pack it badly so I found the best solution to get a good seal is to put a groundsheet right at the top of the bag with my enamel mug on top and the drawstring tightened around this. Any water that does seep through the top of the bag will only end up in the mug now. The waterproof cover that comes with this bag is large enough to cover the whole thing but I also have one from the smaller 25l bag DCCN sell that is a perfect fit over the top of this (whilst being easier to put on and take off) that provides better protection for the main compartment. Both covers are easily stashed in the zip compartment on the top flap.
When the bag is unzipped to enlarge the main compartment it can become quite cumbersome and rear heavy so it is best to try and pack the heaviest things down low in the bag to keep the main bulk resting on your lower back rather than dragging the bag backwards higher up. I wanted to stick a couple pouches on the rear or sides for little things so I don't have to fumble around for them in the large compartments but this only amplified the problem and made it very awkward and bulky to carry such that you couldn't put any weight in them at all. My solution to this was to take a big belt bag and attach it to the waist strap on this bag so I have small compartments for loose things whilst also distributing some weight to my front to balance the bag out. This has made it a lot easier to walk with. As the main compartment is so big I've also put some loose items in molle pouches and just put them in there rather than attaching them on the outside.
The upper chest strap on this bag is only thin like it seems to be on other bags and I would rather something a bit better there but it is at least in a good position to pull the straps inwards without being so high up as to choke me as on some other bags.
I have a little over 20kg in the bag and it is pretty easy to walk around with and the bag feels more than sturdy enough to manage this.
I'm so glad that I chose to spend a bit more and buy this bag rather than go for one of the cheaper ones, because I could tell straight away that the quality is far superior to what they would have been, looking at their reviews! The material looks and feels strong, the stitching is good all over and comes with rain a cover. The best thing about it for me was the option to open it out to 85L. I'm travelling for a year and I'm sure this is up to the challenge. It also arrived quicker than I expected.