Lots of subjective anecdotes in the form of one-sentence "tips" you can leave at places, but IMO they tend to be a lot more positive than Yelp reviews, which tend to be disgruntled people kvetching.
Personally the tips are more useful than Yelp reviews. I don't have time or inclination to read long-form reviews, 4sq tips are much more relevant when I'm sitting down in a restaurant and figuring out what's especially good on the menu.
IMO they made a mistake. The Yelp-killer app should've been separated from the 4sq brand, not the other way around. Foursquare is forever known as "the checkin app", if they really wanted to pivot IMO they should've called it something else entirely.