As Photoshop’s first 64-bit version, Adobe has jumped ahead of most PC and Mac users who are still running 32-bit operating systems. For those using the 64-bit version of Windows Vista, they will experience the ability to work on gigantic files with very little or no lag. When editing photos that are 3-6GB, using this version with a ton of RAM really does make a big difference.
For the rest of us, the OpenGL integrated features can come in handy, especially when using a tablet. OpenGL support aids the 2D and 3D graphics across many different platforms. Even in the Standard version of Photoshop CS4, users will be able to experience a new, ultra-smooth zooming function, as long as their graphics cards support OpenGL.
Also, you can now rotate a photo to any desired angle in a nondestructive way, which makes editing on a tablet much easier.