It works surprisingly good. Tried it out for my hometown "Suceava", a small forgotten city from northern Romania. The information one gets is really useful and seems to be mostly accurate.
When I went to Budapest (this summer), it contained invaluable information about the city and some scams that ticket inspectors pull. I was able to avoid it and help a few fellow passengers because of Wikitravel (now Wikivoyage). I would definitely recommend it, it was entirely accurate in my case, and for the few Greek cities I skimmed.
mostly accurate?
In the world of travel guides, mostly accurate is pretty much the gold standard.