I've never used the OS maps as I rarely visit the UK. I've worked with similar maps in the Netherlands though through a GIS system (also worked in telecom). But

I've never used the OS maps as I rarely visit the UK. I've worked with similar maps in the Netherlands though through a GIS system (also worked in telecom). But when hiking (mainly in Spain) I always prefer OpenStreetMap to the official maps. The problem with the official government maps is that they are official. If a hiking trail is nothing more than a trodden path through the brush, they won't show it as it's not an official path. If they'd put it on there they'd admit it would be a path and be on the hook for upkeep etc. Google Maps is also really bad for this usecase as I believe they get most of their data from the governments. So when it comes to really obscure paths which are pretty essential to hiking, the government maps are not as good. OSM shows how it is in reality, the government maps show how they want things to be :) But like I said, perhaps the UK is different in that sense.