I'd have to disagree. I have both editions, and the while the third edition has essentially the same info, there are far more pictures and color illustrations in it that make it a much more stimulating book.
If you're using B&W for step 3 and have the 2d edition with notes scribbled all over it, then perhaps you should stick with it because of all the personally added content. I annotated a fair amount, but the diagrams and pictures were a draw, so I'm going to read through it for step 3. And UW, of course.