TechCrunch:

For instance, iMessage in iOS 8 now lets you send voice memos and videos that expire unless you choose to keep them. These features are built into the new keyboard, with an icon on the right that you can hold down to record audio, and a familiar camera button on the left that is slightly more tricky.

If you tap this camera button, you are given the same options that you’ve always been given: Choose from Camera Roll or Take Photo or Video. If you hold the button down, however, two second buttons emerge: the top button is a camera and the button to the right is a red, circular record button. As The Verge points out, this behavior of holding down your thumb to send a photo or video is highly reminiscent of Snapchat.

Once you hold the button, you can release and press the camera or record button or simply slide your finger over to those buttons to take a pic or video.

But here’s the rub.

With both videos and voice memos, iMessage lets you review the content before sending it. You can play it back and then choose to delete or send it off into the world for other peoples’ viewing and judging pleasure.

With still pictures, however, the photo is automatically sent the second your finger releases the camera button.

This instant send mode also occurs when you select an existing photo to send in Messages. When you tap a photo in your library, Messages reveals a “Send 1 Photo” button which will send the photo instantly.

There’s a slippery slope between ease of use and unintended consequences. The instant selfie is a great idea. Rather than implement it with a gesture that lies along the path in a typical use case, better to tie it to a unique gesture. Allow people to discover it, perhaps by reading about it in a tips and tricks post, rather than stumble on it accidentally.