Last week, I had to go for some days in Rennes. To book a hotel there, I used the Mappy services to locate hotels near the town center. The problem is that when Mappy can't find an address in a city, it locates it near the town hall. Thus I found a not-too-expensive hotel near the town hall: that was what I expected. However when I arrived there, 21h00 in a cold day, I couldn't find the hotel where it was indicated by Mappy. The problem is that the hotel was 20 minutes far from the city center by bus... It took me 2h30 to find the correct place of the hotel and I found it in an industrial zone with nothing around.
The conclusion of this really bad experience is: do not use Mappy-like services to locate a hotel: better prefer the good old yellow pages and a real map. By the way some other maps are better and simply tell you that there is no result for the asked address: at least they are honest !