Instagram has just got an update that puts it in the design guidelines for iOS 7. The developers have got rid of every shadow and gradient, going for a much flatter style.
The elements mainly stay the same, just the colours and buttons have been flattened and given solid colours instead of gradients.
There has been some minor changes to the main feed - now avatars are circular and the photos span the width of the device.
It's great to see the developers change the app to fit the style of iOS but what puzzles me is why they can't do the same for Android. The Android design guidelines are just as simple and it would fit much better into the style Google has given to Android.