I've used it quite extensivly, big fan. It asks for further details on objects that have already been mapped, which also reveals things that don't exist anymore. It turns mapping into a really fun game with currently 163 different quests. The app also regularly asks you to verify opening hours or confirm the existence of certain objects. That being said, I almost always use it in conjunction with a real map editor, to add new stuff I find or to make more complex edits.