Well, the idea is certainly sound. I can't comment on how well it's made, you'll have to go by reviews. But I can say that most of the systems that clamp the blade like that have two limitations. First is that the thickness of the clamp itself dictates how low an angle you can achieve before the stone scrapes the clamp. For hunting knives and German kitchen knives that probably won't be an issue but you never know. The other issue is that to do longer knives you will have to unclamp, move the blade and clamp again. This can be annoying and depending on how the design is executed it may be challenging to index the knife at the precise same angle when you do reclamp. The arm that holds the stone looks to be fairly long so that might not be an issue with knives 8" or less but it's hard to say.

Lastly I'm not familiar with it at all so I don't know if you're stuck with the stones supplied or if you can use other stones. Just a cursory look indicates they're 6" long; if that's the case then Edge Pro stones may work, and at least a couple companies manufacture stones that size (including DMT diamond plates/stones). There's a company that's known for industrial abrasives that offers stones in that size at this exact second I can't remember the name.