Think of it as a very stripped down and opinionated version of OsmAnd. It lacks a lot of power features, but is extremely fast and all of the options are easily available and work out of the box. So it's great for everyday use (especially in cities with a lot of POIs) but not as good for in depth travel and route planning.

For example, I've used F-Droid OsmAnd extensively when planning my trip to Japan, because its guides, WikiData and Wikipedia integration are godsend for finding interesting places to visit, but used CoMaps when I was there to look things up and build routes. I'm also exclusively using OsmAnd for writing GNSS tracks because I can fine tune the parameters of measurements it captures.