I've been on and off with D23 for about 40 years, but I think I have finally kicked the habit. The easy thing about it is mixing and using it, and you get a smoother contrast range. The down side is that it's almost entirely solvent (sodium sulfite in abundance), and the grain and sharpness both come out mushier than my favorite D76. Also, highlight contrast suffers, and there's none of the nice sparkle of D76. I won't even use it for x-ray film now, which is a high contrast film on its own and likes softer developers, but even with that, D23 kills the sparkle in the highlights. So I'm left wondering what the point of D23 is, after ease of use.
I do not use it as a two-part, with a B solution. That might change my feelings about the sparkle, but probably not about the mush.
But it sure is easy to mix.