In Photoshop CS6
- Better context-aware fill and the ability to take objects entirely out of an image (not very useful), or move the object around in an image (very useful). I am desperately looking for a way to extend the background of an image, stock image photographers always crop to narrowly around a subject, leaving no space for text. The current tools are not there yet.
- Sometimes it might be the hidden things that are best. I have just the impression that the general selection engine to isolated subjects from their backgrounds is better.
In Illustrator CS6
- The pattern generation engine is much better. It is cumbersome to generate patterns of repeating objects in PowerPoint or Keynote. In Illustrator it is easy, and you can apply them to any shape as a fill.
- Photo tracing. It is now very simple to turn a photo or hand-drawn sketch into a scalable vector image. This will make it easy to convert images into more neutral silhouettes in presentations.
There are a lot more new features that will appeal to heavy users of both programs. Should you upgrade as a casual user? Your call. Since I am a professional presentation designer, I just install the latest software without really making the trade off every time. What do you think, if you have upgraded, was it worth the investment?