I've looked into them when buying a new printer. They're the cheapest laser you can buy, but the refills include the drums, which makes them way more expensive. They're also extremely small for a laser.

I ended up buying an epson ecotank, which is a lot slower than a laser, but it's still on the original ink after 800+ pages and it's never been problematic even if I leave it for a couple months without printing. Doesn't seem to clog up like others have reported