When I bought my s8 with came with a promotion inc the genius Samsung keyboard.
The first keyboard I got didn't worked at all. I've tried to double shoot and nothing worked so I contacted the promotion team and they asurred me that I'll get a new one. Rather than express send the new keyboard I had to wait for them to process my claim, which is stupid because they already confirmed the first time. So after few weeks without the keyboard.
The new one is a bit weird..it dosn't type properly and you need to hold the key in order for it to recognise it and type it..
Forget about typing normal with the keyboard, as the system is not recognising when you press the keyboard, and I've check the various setting and nothing seems to work.
Mine works pretty solid. 7.5/10. I did notice some touchpad gesture related annoyances and sometimes I needed to hit a key with extra power for it to register but these are few and far between at this point. I recently (within past week or 2) downloaded some new firmware for the keyboard and I believe I have had maybe another 1 or 2 updates aswell since receiving it. Dunno if you can check what firmware it is using?
Overall I'm quite happy with mine. It even survived about 300ml of sanitiser spray liquid being spilled over it whilst it was powered on and in use (I unclipped it when I noticed and a river of liquid was pouring from inside the body and from the keys but after 2 weeks of drying it works perfectly. I also threw it at a wall and hit it hard enough for several keys to became partly dislodged/stuck and it's still going strong. Obviously I'm extremely lucky it still works and don't take my experience with it to mean it is bash proof and waterproof as it is certainly not. Maybe you could try to record some of the issues you have whilst using it and show it to Samsung? I'm sure if you found the right person they'd replace it if it was obviously not working well at all. However I'm not sure what warranty you'd get if it was a promotional item.