qbro is a good instagram alternative app, if you’re looking for one of course, and its just been updated with iPhone 4S compatability, better late than never and a minor bug fix. This app retails for $1.99/£1.49 and you can download it here.
✓ Touch Exposure & Focus Separately (Using Multi-Touch)
✓ White Balance Lock
✓ Zoom, Timer, Big Button, Rotate
✓ Take a photo / Load a photo from your camera roll
✓ Add Stacks place like your basic camera
✓ Save in Maximum Resolution
✓ Front camera reverse on/off