The snicket is a little overgrown, but the area around the snicket is all well preserved and developed, the original mill buildings put to new uses as hotels, offices, restaurants and such like.
The snicket itself leads to a railway bridge and then a footpath that takes you up to a main road and I expect that the footpath is a bit overgrown through lack of use rather than deliberate neglect. I also expect that, unless you are interested in photography or Bill Brandt's work, then the location probably means little to most people. A lot of photographers will probably be unaware of Bill Brandt's Halifax work, much less anyone else, so the location is more of a curio / footnote in history.
I'm happy it's still there and still closely resembles how it looked when Brandt made his picture.