Tripadvisor lists tour options for many of the available attractions. Many of the individual tours have lots of recent reviews so you can get a better idea of what the experience will be like.
"Most Reviewed" for popular restaurants, "Highest Ratings" for well-received restaurants, use the # of reviews the popular restaurants as an anchor for had to evaluate the restaurants with the highest ratings. For example, if popular restaurants have ~1000 reviews, then well-received restaurants with >4.5 stars and >200 reviews is pretty good. A restaurant with 5 stars an 20 reviews might not be as solid.
The best match is usually the result of some continuous feedback loop of recommending the same set of restaurants to people over and over again, instead of the best restaurants in the area.
If enough people have posted reviews repeating the same key words (e.g. tiramisu), Yelp will highlight them. A good sign of something you should definitely order if it's your first time at the restaurant, or something that the restaurant does particularly well.
They show from oldest to newest, even though the newest photos are more relevant. The desktop version of Yelp also has an old photo display system where you have to click to reveal each page of photos.
In what looks kind of like Google street view, looking through photos is decidedly awkward. Luckily, Google has an alternative, just google the restaurant in Google Images.
The same restaurants will typically get between .51 points higher on open table, the audience usually gives between 45 stars as long as there weren't major flaws. This is partially do to the fact that service/ambiance plays a larger role in the ratings than other platforms. Since most restaurants that take reservations value service/ambiance, the ratings are skewed upwards.
If you search sushi in New York City, the #3 result is Five Napkin Burger, which, while it serves sushi in addition to its famous burgers, is no where close to being the #3 sushi restaurant in NYC.
With so many points to give, restaurants that fall below 24 all become questionable. Either that, or users are forced to convert it to a 5 point scale in their head, 24 = 4 stars, 18 = 3 stars, etc.