Visit May 19. On my short trip to the northern part of Jordan I visited some great TWHS, like Jerash or Umm al-Jimal. And I visited As-Salt.
I parked my car near the town hall and went to the Archeological Museum. There I got a poorly copied map of the most important buildings related to the WHS. I spent my time hunting down these buildings.
As-Salt is certainly not a city that lets your jaw drop. What Unesco describes as “a blend of European Art Nouveau and Neo-Colonial styles combined with local traditions” were to me rather boring square buildings. The oldest part of the city is not unpleasant, but also not outstanding. Certainly it is not photogenic city. The cars, narrow streets, open cables and lack of real highlights make it hard to get some good shots. Maybe if you find a good guide that can explain the value of the city on site, you get a more satisfying visit. For me, this was absolutely no highlight in a country I otherwise quite like.
As-Salt is very close to Amman. You can easily squeeze it in on your way to the Baptism WHS.