I used to be a fan, and used them heavily for years. They stay sharp... for a while, and then there's no practical way to re-sharpen them. You get a couple good years out of them and then a lot of mediocre to bad years.
Running a steel knife through an electric sharpener once a month (a 2-minute operation) keeps it feeling consistently like new.
It's cheaper than an electric sharpener and doesn't carry the risk of taking off too much material from a blade due to overenthusiastic use.
I am 100% certain that there are multiple people on this thread that could tell me I'm getting less optimal results than their tools and/or method. I don't care. I'm getting results that work when I cook. I don't trust myself to get the angle right with a diamond stone.
Pull through sharpening creates an edge that does not last. This channel has great explanations about this and what to do instead: https://youtu.be/pagPuiuA9cY
That is an amazing video. I can confirm that the methods are correct, he mentions exactly what I've been doing for years, explains and demonstrates very clearly.
I have one, I use it on my knives every 1-2 months. My knives will last decades rather than "lifetime" but I don't care... they're always sharp and I don't have to work at it. I can buy new knives.
Running a steel knife through an electric sharpener once a month (a 2-minute operation) keeps it feeling consistently like new.