It not only has the best volume-to-weight ratio, but also smartly designed to fit in all the necessary travel supplies in the most efficient manner.
I recently used this product in Goechela trek. Though slightly bulky but it is awsome, comfortable.
I think I am one of the very first customers in India to buy this bag as soon as it arrived in Hyderabad Decathlon store. Well, There should have been a "Very Good" between your "Good" and "Excellent" rating. I am rating it as "Very Good" as it serves all purpose of a trekker, camper and traveler. The back open system like a suitcase has made it unique in design, and it's a delight thereby using the product. The top portion of the bag can be used as a side-satchel - that's another great feature. Though a locking mechanism doesn't help much in terms of security in this kind of backpack, I must say, it's a unique feature and definitely a plus.
The only downsides I found are that the bag is quite heavy, even when it's empty and that the rain cover that comes with it is also very heavy and takes a good amount of space, even after folding up neatly. The rain cover, I feel, could have been little thinner, like a light plastic one. If you are a serious camper like me and are carrying your tent / sleeping bag etc along with the bag, it may be a bit heavier while ascending steeps.
Else, a fantastic product.
Comfortable and roomy and has a very handy day pack that attaches to the backpack. Open to the front so it's easier for packing. Used it for 2 weeks while backpacking in Europe and was very happy with it!