If you don't own Apple's dedicated "Portal 2 - The Final Hours" reading device, you're in luck. It's now available on the PC and Kindle. The PC version features interactive elements, exclusive photos, insider movies, timelines, and more. The Kindle version, on the other hand, is handsomely bound, assuming you bought a leather carrying case for it. You read that right - the PC version is now available on Steam.
PC Version
iPad Version
Kindle Version