Bastion for iPad is now a universal app with support for iPads 2-4, iPhone 5, iPhone 4S and 5th generation iPod touch. Developer Supergiant announced the update on its site today, noting it includes upgrades such as full optimization for the iPhone 5 screen and iCloud support (to transfer saves).
The developer previously stated it "felt the game experience would not translate well to the iPhone's smaller screen," but the launch of the iPhone 5 had them take another look. Bastion is currently $4.99 and the update is free if you already own the game on iPad.