For years I would go to Paris, armed with a guide book, and experienced the most wonderful city in the world. Today, in addition to using guide books, phone apps, and audio guides, people tour Paris on their own. However, in order to get the most out of a trip to Paris, hire a professional, licensed tour guides. In order to be a licensed tour guide (and they do need to be licensed), a guide goes through a rigorous process of being certified. See the blog post for recommendations on Paris tour guides.
When I originally started traveling to Paris, I would tour on my own with maybe the assistance of a guide book or an audio guide. Then, for my small group tours to Paris we started using professional licensed guides. By the way, all guides in Paris (and many other cities) must be registered and licensed. I found that these professionals were not only able to explain the history and culture of Paris, they were available to answer many different questions, which of course cannot be had from a guidebook, audio guide, or phone app. Read my blog post to find the best Paris guides.http://www.travelingprofessor.com/