I’ve been using this app on 3 generations of i-Things over 4 or 5 years - since before Navigon was purchased by Garmin, in fact. Ive used it while traveling in most of the countries of Western and Central Europe, in Scandinavia, and in about a half of Eastern Europe, on roads ranging from Autoroutes to cow paths. It works well.
One of the app’s strengths is the Map Manager, which allows maps to be loaded and unloaded depending on which countries my trip will be in, therefore saving the footprint needed for hold the whole map set. Maps can be loaded “on the fly" whenever the device is connected to a Wi-Fi network.
One of my strongest criticisms is that in France (in particular) the “lieu dit" names, usually just naming a single dwelling, appear at the same level of visual importance as a town of 20,000 people. That makes it difficult to find villages and towns amid the visual clutter of named places. There should be a way to filter the names by population, so that overviews show only “real” towns and villages. Even a cutoff size of 100 people would remove almost all lieu dits from the map.
Ive bought several of the in-app enhancements: Panoramic 3D (worth it for navigating by large-scale landforms), Urban Guidance (worth it if you’re going to be walking around in city centers), and the Michelin RedGuide (hasnt been too useful, since I mostly sleep in privatzimmer and pensiones, and find out where to eat by asking the locals).
I use TomTom’s products in North America, and believe that both companies are very competitive with regards to features, usability, coverage, and performance.