It combines the versatility of using your own paper, like a three-hole-bunch binder, but with the reliability and compactness of a wirebound notebook. Choose whatever paper you like, print out your desired grid system, reorder pages, add tabs, etc. and still have the same notebook.
When you need to archive pages, you can remove them from the notebook and throw them in a scanner.
I'd say the initial cost of the notebook and punch is steep, but not if you're comparing to $20 hardbound notebooks like Tomoe River or Moleskine.
Apparently, paper has enough "structural stiffness" or whatever (don't know the detailed physics), that it won't pull "away" or "up" from the discs by itself. Forcing a page out can be done for sure, so you need to be aware of this and put the paper in/out of the discs with a special kind of gesture/movement, that bends the paper instead of tearing it. Still, both the static forces and each in/out gesture do put a bit of stress on the paper, so you tend to prefer a slightly thicker kind of paper for this than in typical notebooks. Common xero/printer paper with 80g/m2 is decent enough for me, although if really needed, thinner paper can also work, but it will be much more flimsy and prone to falling out. Still, if some of your pages get tired around the holes, you can do an "emergency repair" by taping them over with e.g. washi tape, and re-punching the holes. I found the repair procedure imperfect for a number of reasons (esp. that I can't seem able to keep the page from warping when I apply the tape), but still better than letting the pages fall out, so I only use it as a last resort.
What I found even more interesting, is that the technology was invented quite long ago - I think I read that it happened even before the 2nd World War, though the earliest concrete date I can find now is "before 1948" (see https://en.wikipedia.org/wiki/Disc-binding and https://atoma.be/en/the-atoma-quality/). IIUC it's patented by the company founded by the original creators, https://atoma.be. But apparently it's been since licensed (?) to some other companies, and/or the patent has expired. Notably and fortunately, most of the current producers stay compatible with the original system (the general dimensions, positions, and distances of the holes are the same), so you can exchange the punches, discs, pages, and other accessories. That said, as shown in the link above, there are slight variations in the shape, which results in more/less friction when turning the pages depending on the exact shape of the hole in the page vs. the exact shape of the disc's cross-section. Also, weirdly to me, each of the subsequent companies tries to sound like they're the one and only creators/"innovators" of this technology, while (usually) following the
Anyway, there's some more info you can gather from teh Internets and youtube, and there's some small community on reddit: https://old.reddit.com/r/Discbound/
I don't recommend buying their refills. The benefit of the system is to buy your own paper stock and print out your preferred line/grid system, and punch it yourself.
https://www.levenger.com/CIRCA-326/ABOUT-CIRCA-1233.aspx
Arc is cheap and available in person at Staples.
It combines the versatility of using your own paper, like a three-hole-bunch binder, but with the reliability and compactness of a wirebound notebook. Choose whatever paper you like, print out your desired grid system, reorder pages, add tabs, etc. and still have the same notebook.
When you need to archive pages, you can remove them from the notebook and throw them in a scanner.
I'd say the initial cost of the notebook and punch is steep, but not if you're comparing to $20 hardbound notebooks like Tomoe River or Moleskine.