ditto, google maps reviews are weirdly inflated with almost all restaurants having 4+ stars, even terrible ones

yelp's review quality has been on the decline as of late though. it used to be great

Seconding this. Yelp reviews have their problems but at least there's always content in the review and I can validate some of the reviewer's reputation if they're being suspiciously positive/negative in their review. Most google ratings I see have very few reviews behind them, and most of them are under a sentence long.

I don't think you can really use any absolutes here. It depends very heavily on where in the world you are.

How useful yelp is varies enormously if you travel. In the U.K., as an example, Yelp can feel like a wasteland - often little or no reviews, and it has nothing like the mindshare it enjoys in the US. As a result many businesses do little or nothing to keep the information on their Yelp page accurate, it’s barely even on their radar. In the US one can often use Yelp almost as a verb in a conversation (“let me Yelp us somewhere for lunch...”), this is met with blank stares in much of Europe in my experience.

The lack of good data on Yelp in the U.K. has indirectly hurt other players there too, when Apple maps first launched business location information was largely drawn from Yelp, which basically seeded Apple maps with very bad information. Locations were wrong, many businesses that simply didn’t exist anymore would appear. Granted it’s been years since I last checked, but in the first few years of Apple map’s operation it was a pretty significant issue. This methodology worked great in Cupertino I guess...

While I use google reviews more often than other review sites, I know it is a problem. A big chunk of the issues has to do with the whole "local guide" or whatever its called program. People are incentivized to leave reviews anywhere they can because it makes them seem prestigious, so they spam all the restaurants they've not been to or don't care for with negative reviews. This is also a rampant issue for tourist destinations, entertainment locations, local businesses, etc.