The nice part is that (almost) nothing in the actual rules is changing. Instead it's clarified rules, expanded explanations, extra options, character backgrounds a la Electric Bastionland, and such.
It's not replacing 1E, it's just more of it.
Plus a nice to hold hardcover print, for those of us that have a sickness where the only cure is more nice looking TTRPG books to put on our shelves.