The expandable zipper is the reason I bought this, and it works exactly as promised—I went from a cramped day pack to fitting a hoodie and extra shoes for my flight home. The divider also kept my laptop separate from my gym clothes, which saved me from digging through everything at the gate.
Took it on a weekend trip and the expansion from 28 to 32 liters really came through when I needed to stuff a jacket and souvenirs on the way back. The divider kept my dirty hiking shoes away from my clean clothes, which was a lifesaver. Only wish the side pocket had a bit more depth, but overall it