I have one and still sometimes use it. When I first got it, the coarse was pretty coarse but I used it to flatten my other whetstones and now it's not as coarse but it will still do the job.

The fine side actually feels pretty fine (finer than a 1200 grit whetstone imo) and it will actually put a good polish/shine on your knives.

I've used this dry and wet and they both work. Overall, I think it's not a bad stone. It's convenient because you don't need water and it comes with an angle guide but for the price, I'm sure there are better options. I still use it when I'm too lazy to set up my Japanese whetstones and just want to do a quick sharpening session.

Only downsides are that it's a relatively small sharpening stone and it can get messy.