Visited dec 2018. Humberstone is a little out of the way in the north of Chile but I love these kind of sites so we suffered the extra 6 hours on a bus from San Pedro de Atacama to get to Iquique. Fortunately domestic flights are cheap in Chile (for now) so could fly back to Santiago easily after. 

The site is easily visited by local bus from Iquique, dropping you off on the main highway out front. Humberstone and Santa Laura are easily visible from there. As the representative of over 200 similar sites in the region I can only imagine the poor state the others must be in. Parts of Humberstone (the plaza, theatre, market a few homes, etc) have been restored and the museums are full of quality detailed information, but what I liked the most was wandering through the rusted fences and into the broken homes and factories still barely standing. Without more support most structures might not last much longer as is the worry with Santa Laura. Unfortunately we spent so long in Humberstone that we didn't have time to walk the 2km over to Santa Laura and see it as well. I'd suggest an early start to be on the safe side. 

Hard to believe that not so long ago this region at its peak was producing nearly 90% of the world's nitrates and now it is nearly forgotten, wearing away in the desert. Overall a very worthy inclusion of a globally significant site.