I use it for Tides/Current planning with a great off line app called Navimatics. This app also includes all of the Active Captain data in an offline mode. I update once a month or so online. Actually the best use is to use it as a manual repository. I have a good 80% of my manuals stored on it and it is extremely handy. I am thinking about scanning the other paper manuals in so I can have that same access. I do keep the paper ones on board but they are buried deep deep in a locker.
I do have the view that using general purpose O/S's as the basis for a navigation system might not be wise. I prefer purpose built firmware that is built from the ground up for the use of navigation (Raymarine, Garmin, Simrad...). It's just me. I shutter to think that there are people out there solely dependent on a Windows based system to keep them alive. Apple IOS is somewhat better, but..., again that is just me. And... there is nothing like taking a pencil to a paper chart to set a coarse that was derived from the use of the ol' M1 Brain Housing Group.