Skobbler for iOS is a great example of the advantages of open source (software). It’s a great navigation software, and at 1,59€, it costs almost nothing, especially compared to Navigon (89,99€) or TomTom (69,99€). The country you buy ‘Skobbler’ in is included, maps for other parts of europe or the world are a few euro.
I uses the OpenStreetMap catalogue, so the quality may differ. But considering Skobbler’s price, that’s a risk one can take.
I made two roadtrips with Skobbler, one to Bremen and one to Denmark. There were no errors, problems whatsoever. The audio commands just before you have to take a turn are very well timed 98% of the time. Those missing 2% are to be fixed, but I came across the same problem with a built-in BMW navigation system. You shold give Skobbler a try.