I visited this WHS in Summer 2019 en route from Zatec to Augsburg, Germany. I focused mainly on the Czech side even though I drove through other minor sites on the German side too.
Coming from Zatec, you can't but notice the huge power plant (which is quite of an eyesore!) before getting to Jachymov. Like the rest of Northwestern Czechia, Jachymov has definitely seen better days even though the inscribed sites are quite in good condition with several information boards in English too. The view from the winding road leading to Jachymov is that of an old mining town like many others on the list.
The most interesting site in Jachymov is the Dul Svornost mine which has been operating since 1530 and is one of the oldest complexes in Europe. It is also the last functioning mine in the Jachymov region. Originally, the mine produced silver, cobalt, arsenic and bismuth. In the 19th and 20th centuries, it was a source of radium ores and uranium, hence the peculiar monument of Jachymov just before entering the town. Since 1964 the mine has been used to provide therapeutic radon water (which is believed to be up to 13,000 years old!) for the Jachymov spa. For those that are more keen on industrial heritage sites, there are several trails along what is known as the Stribirna Stezka/Silberstrasse.