These were the cat's ass when I was into the analog scene. Sony and Mitsu made them. The idea was that the stylus remained perpendicular to the groove and there was virtually 'zero' tracking weight on the needle. I don't think there has been any improvement in 30 years in this regard.*
I don't know how a single diamond stylus can genuinely reproduce stereo separation, frequency and volume with a single analog input which depends so heavily on wear of the stylus and groove of the record, not to mention the speed and angle of the tracking groove.* As far as I'm concerned, get as much musical information faithfully reproduced as possible, and shape it from there. But to the human ear phono still sounds pretty good. It depends on how you listen to your music I guess, and how you like it to sound. I like a lot of presence. I want it to sound like I'm in the cathedral recording it. NO... like I'm directing it! Of course, the phono input is just the beginning. The rest of the stereo system must also faithfully amplify and reproduce what you're listening to.
* I have read that Edison had it right with his tubes. The frequency was recorded with a vertical component, rather than lateral. And his cylinders stayed aligned with the tone arm/stylus. But they only contained one track at a time and packaging was not as efficient.