I've tried using it over the years but I never liked it because there was no information. So last night I looked at my local city and there is almost no information at all. I spent a few hours last night adding buildings and restaurants and removing incorrect items. It was actually kind of fun and therapeutic and I plan to do more of it tonight. My girlfriend thinks it's dumb and I'm wasting my time because Google maps and Apple maps and Bing maps exists but she just doesn't understand open source.
Edit: Apologies, I just realized this question is not Linux specific.
It's not even so much about F(L)OSS for me, it's mainly about privacy. Haven't contributed so far, but been using it through Organic Maps. OSM lacks no address in my town, and that's enough for me. I only need a map to get frow A to B, and I'd already know what's at B if I'm going there in the first place.
After trying a bunch of FOSS map apps, Organic Maps comes across to me as completely superior. It's not as good as Google Maps for finding businesses and restaurants in most cities, but it's vastly superior for trails in the country side.
Also, you can contribute to OSM directly from Organic Maps, so if a restaurant is missing it can be added in a few seconds. :)