We used them when we moved, and it was a dream. Hassle-free delivery. The boxes were light enough for me to carry, stacked well, and saved us TONS of space when we were unpacking.

I chose Frogbox not for any environmental reason, but because I didn't want to go through the trouble of finding boxes for our move, and because I didn't want to further attract silverfish into our new place (they love feeding on paper and paper-based products). It was just a bonus that FB delivers and picks up after work hours, and that their boxes eventually made us more space-efficient during our move. All of the boxes were the same size, so there was little wasted space in the back of the van where our boxes were.

All in all I'd really recommend them. No surprises, the price and service were exactly as advertised, and they ended up saving us a lot of time in the end. I'm planning on using them again when I move in a few months.

As a side note, knowing that the boxes had to be returned after a week prompted us to unpack faster. The entire apartment was set up 5 days after our move. Success!