It's no secret that Instagram is a fantastic photo-sharing app. One thing it doesn't do, however, is let you converse privately with user Instagram users. If you have friends on Instagram you'd like trade comments with that won't be seen by the rest of the Instagram community, give iPhone app InstaTalks a whirl.
To get started, you will both need InstaTalks, which creates a bit of a Catch-22 if you want to message an Instagram follower and have no way to contact them other than Instagram. When you first launch the app, you will need to log in using your Instagram information. After signing in, tap the people icon button from the bottom menu to see a list of your Instagram friends and followers.
Tap on a contact to send a text to them via InstaTalk. You can also send them a picture. The app was just released today, so all of my Instagram followers were listed as offline. You can also add contacts to a favorites list by tapping the star in the upper-right corner. And by tapping the button next to the star, you can view thumbnails of the Instagram photos of that person. Unfortunately, tapping on the thumbnail does nothing. From the thumbnail grid, you can tap the camera-icon button in the upper-right corner to leave the app and open Instagram to view that person's profile. It would be useful not only to view photos larger than a thumbnail from within InstaTalks, but also to start a message thread about a particular photo.
There are other views in addition to the list of your followers. Tap the thumbs-up button to see a grid of tiles of popular Instagrammers. Tap on a tile to begin "InstaTalking" with one of these people, provided they, too, are using InstaTalk. Tap on the map-with-magnifying-glass button to search for other Instagram users in your area (I tried this and found none; again, the app just came out).
Lastly, the app acted buggy this afternoon, occasionally freezing and closing.