If you really just want a map, go use OSM. I love it as well and even contributed. But Google Maps is much more than OSM. The biggest difference and most important feature is its real-time traffic. OSM is just a totally different product seen through the car navigation lens.
For me the killer Google Maps feature is using it as a search engine. The POI data on OSM has low coverage, is often out-of-date, and lacks reviews, so while it's quite good for (non-car) navigation, it's not very useful at all for finding places meeting certain criteria.
