Solid 4 out of 5 stars. Be aware that the bag expansion is at the very back of the backpack, as opposed to in the middle pocket where all of the organization is. That means you cannot expand the backpack to hold things in the middle pocket (where your laptop pocket is), such as a book or a 3" binder. Instead, you will have to store them in the back section of the bag, where there is no organizational pockets and requires the 3-sided zip around to open.

The other flaw is the water bottle pocket. I get why they want to keep the sleek line of the water bottle. But because the water bottle pocket intrudes into the middle pocket, you really can't use the middle pocket to store anything with any depth such as a book, a binder, a file folder, etc. And, it really only fits tapered water bottles that have a narrow neck. My 24oz trail hydroflask that does not taper at the top doesn't really fit in the pocket easily -- it's super tight and difficult to get in/out of the pocket. (If the Knack design team reads these reviews, I would highly suggest you make the water bottle pocket be one where you can fold in the pocket if you don't need it, but when you do, the pocket expand outwards with an elastic top.)

Final thoughts: this backpack is a great option for travelers where you're looking to store clothes in your backpack but you don't necessarily need quick access to the items. But I would not recommend the bag for business commuters--there are better options out there where you can expand the bag to gain quick access to documents/binders/books without having to go through the 270° zipper shenanigans. And the water bottle pocket is not a great design.

I regularly commute by plane between home and work and carry on only this bag. There are two great aspects of the bag. First, it allows for excellent organization. As the saying goes, there is a place for everything and everything is in its place. Second, it is versatile. The expanding feature allows me to travel small when possible and larger when necessary.

Knack has finally found the Goldilocks size for their backpacks. I have the Series 2 Med that has been my go to bag for some time. It works great, but I never liked the side zipper for the laptop and it was a touch big for everyday use (but great on my last 12 day overseas trip). The new Small series 2 addresses both these issues perfectly. I love the top loading laptop feature and it still handles all my accessories and spare clothes for a two day trip, but for everyday work it meets these needs without being too bulky. It is amazing the difference in feel for just a small change in dimensions. I had hoped the slig bag would solve the size issue, but found it was too small and the pockets proved to be too loose (no velcro or zippers on the inside), but now Knack has redeemed themselves and more.