It's very intuitive and makes you learn just how detailed and specific map data can be. Can't say much about missing features since I don't event know what can be done.
Recommended experience, it's like playing Pokemon Go without the evil part :)
Open-source software and data are obviously public goods I support. I was just pointing out that the only "evil" parts here are rent seekers reselling this data and the military... not the people assembling the data (players).
Maybe it's a useless nuance, but I don't think Pokemon Go gamers should feel/evil or even that they should be careful the next time they try to entertain themselves.