If we are looking for opinions I will share my experience based on the only single one example that I owned.
It may sound harsh, I'm just being honest. I have owned over four dozen S&W semiautomatic metal pistols (never owned any S&W tupperware) and this 559 was easily my least favorite.
The finish was absolutely unimpressive and this was a NIB/new old stock example. I wanted to think "nice carbon blue!" But it wasn't, it was black, and did not look like any typical S&W blued finish to me.
The action was the polar opposite of smooth. The safety/decock operation was harsh, clunky and gritty. The DA and SA trigger pull, feel, break, over travel and everything associated was literally the rock bottom worst of any 1-2-3rd Gen I have ever handled and I am not using artistic license -- just sharing the truth as I saw it.
I've owned eight examples of 2nd Gen Smith & Wesson pistols and am firmly entrenched in my (strong) opinion that the 2nd Gens were the low point of a phenomenal and historically significant design.
I believe that the 1st Gens were built by skilled craftsmen with parts that needed to be made to work. I believe the 3rd Gens and especially the later 3rd Gens with the black MIM parts required a lot less hand fitting and were mostly all quite smooth. And I believe the 2nd Gens were right in the middle -- parts that needed love (and got very little of it) rather than parts that melded well with each other in the 3rd Gens.
I make a distinction for the 745 as a fantastic 2nd Gen but the 9mm 2nd Gen guns are a class below all the others in my experience of dozens of them. My 659 is smoother in all aspects than my 559 was. Some of that might be the stainless finish? Some if it might be the many thousands of rounds through it. Some of it might be a "Tuesday gun rather than a Friday gun" but I like my 659, crude though it may be. My 559 was an absolute dog.
49 S&W semiauto pistols over 3-1/2 decades, that one was ranked #49 for me. And I would have to think a bit to figure out which would be #48 but the 559 wasn't close to whatever #48 is.