I’ve used the os app for years and os maps for even longer. The maps are outstanding, but the app is too unreliable to count on. Unlike other mapping apps where you can work in an offline mode, when there is a problem with the os servers, you are logged out and unable to access your downloaded maps. This can be a critical problem, so I consider the os app to be more of a planning tool than something to rely on when I’m outdoors. There are several other buggy aspects, but most can be worked around. And as a planning tool, the os app is very helpful. It’s worth having just for the convenience of having the excellent os maps at your fingertips.