Yelp is one of the.
During a recent trip to northern California, I used it to find restaurants in Santa Rosa -- places I would have missed without it, and places I ended up absolutely loving. (Until next time, Flavor Bistro.)
But the app has long suffered from one irksome limitation: Although you can write a review on your phone, you can't actually publish it. It remains a "draft" until you get back to your PC and finalize it in your desktop browser.
With the recent release of Yelp 7.0 for iOS, now you can do more than just draft reviews: You can publish them as well. (The Android version will be similarly updated in the near future.) What's more, if you've taken any photos of the business and/or its wares, they'll appear in-line with your review.
Just pull up the listing for any business, then tap Add Review. You'll see the option to add a star rating and a full-text review, followed by a chance to add photos if you like.
However, the app doesn't give you all the options afforded by the Web interface (like specifying the price range, whether it's good for kids, availability of Wi-Fi, and so on). For that you'll still need to hit up your browser.
Wondering what happened to the Tip option? It's still there: Just scroll down to the bottom of the business listing until you see the Add Tip button.
Just remember to count to 10 before you leave a bad review. At leastafter Yelping her dissatisfaction with a business.