I'd encourage potential buyers not to get their hopes up when it comes to quality fit and finish, especially if they have arrived here after hearing about the original IBM Model M keyboard. Fit and finish are quite crude in places. This isn't a solid unbendable rock with perfectly moulded plastic, in fact in places it's less polished than most mass-marketed keyboards.
That's where the bad news ends.
As a retro-looking object, it works well in the right setting.
As a tool, it's remarkable.
I bought this purely to improve my typing, as I've been getting very frustrated with how many mistakes I've been making recently. The difference is huge. Not only do the loud clicks to give audio feedback, but the shape (curve) of the keyboard and the huge effective height difference between one row and the next really helps give constant feedback as to where exactly your fingers have landed on a key. If you've overshot a bit towards the back of the keyboard, instead of accidentally pressing the key behind, the huge 'cliff' of the row behind will guide you to the correct row and let you know where you are.
It feels like I'm being forced to put a bit more effort into typing with this keyboard, by fully pressing and lifting off each key, but it seems to work. I can type very fast and with very few errors.
I can only imagine how much time and effort IBM put into testing and prototyping the design decades ago, and whatever you can say about fit and finish, the design principles are all carried through to this modern model.