If it's stainless steel, it's not a Model 19, it's a Model 67 (crap, I can't never keep that conversion straight).
If it's shiny and stamped Model 19, it's nickel plated.
In my opinion, the Model 19 is simply the finest combination of weigh, ergonomics, power, simplicity, etc. ever put into a .357 Mag. revolver. It truly has no peers, which is why I have 3 of them.
However, the Model 19, after lengthy service with full T&B (tilt & boogie) .357 Mag. loads, can shoot loose and require servicing. That's the reason why the 586/686 models were developed -- to add beef to critical areas to allow better service life with FTB loads.
Will a Model 19 rattle loose after a cylinder full? No. Will it shoot loose faster than a 586 or a Model 28? Yes, that's simple physics -- the same power levels in a smaller package wears the smaller package faster.
Is it still the finest .357 Magnum revolver ever produced?
Without question, yes.