With the Android app, pinning a photo from the Web is simple, so long as you can get the function to work. I ran into problems using different browsers on different devices, so be sure to check if this function works with your setup. While using your browser, go to Android's built-in share menu, and choose Create pin. This lets you choose which photo to pin, select a pinboard, add a description, and so on. The workflow here is exactly like that on the Web site.
Meanwhile, since the Safari browser on iOS devices doesn't play well with other apps, iOS users have to install the Pinterest bookmarklet to pin something from the Web. Alternatively, you could paste a URL into the Pinterest app's built-in browser, then use the Pin It button, but that's a hassle if you do most of your browsing in Safari like most iOS users.
With Android's Share menu, you can pin items right from the Web. Be careful, though, as the function may cause a glitch with your specific device or browser.
(Credit: Screenshot by Jaymar Cabebe/CNET)One thing I noticed is that it's tough to create new boards from the Pinterest mobile app. Sure, when you're pinning an item, it gives you the choice to create a new board, but it doesn't let you do so outside of this context. This makes it difficult for users who need to create several boards in one fell swoop. Also, the app doesn't let you edit board descriptions or profile information, which is disappointing. And finally, moving pins between boards is just as difficult on the app as it is on the Web. This is something that Pinterest badly needs to fix.
If you mainly want to browse through pins, follow new users, and search for specific items, the Pinterest mobile app rocks. It's a beautiful app that offers an incredibly rich experience, similar to the full Web site. On the other hand, if you need to edit your profile or add new pins from the Web, then it may disappoint you.
