For me, I have not seen enough changes to upgrade PS in the last several years, however, with the new CS6, I believe the time is nigh!
There's a new graphics engine called Mercury, an advanced, non-destructive crop, new RAW import with amazing flexibility, lens blur, shadow and highlighting and rich cursor support which give you information by your cursor. Auto-saving, auto-correcting and the new layer system are certainly items one can check off the to do list.
Btw, the all new interface has a default dark gray color, however, you can change this as well as the background to revert to the classic look or go even darker. The new default certainly helps focus attention on the image.
Grab it here and give it a whirl!
http://labs.adobe.com/technologies/photoshopcs6/