Given reviews from Amazon, classify those review based on their content into two classes: Negative or Positive.

I've noticed very little degrading of the sound, if at all, and this is rare in most extensions. The cord is thicker than usual for both the positive and negative polarities - a separate wire for each - and I'm quite pleased with this, will perhaps get another because of its thickness. I now have great headphone sound within a twenty-foot range - just what I was looking for. Even if you don't need 15-feet of cord, I would recommend this over the shorter 10 foot cords where the wiring is about half as thick and not likely to hold up over time...I subject all my electronics to heavy use. Plus, the best extensions for Grado headphones go for $40, and I'm quite satisfied saving over $30 by having this one.
Positive

The best thing I found in this book is the picture on the cover. Well, actually the uncropped version in chapter 5. Beyond that, I found everything else to be non-practical from a design perspective. A photo of a filthy dust collector area when discussing the advantages of central collection or electrical wiring that would never pass inspection is typical. I'd rather see plan views of real shops that work with reasons for the decisions made.
Negative

It took me forever to finally get this gem, but it was so worth the wait. Some of the best music I've ever heard. They had it all! Wouldn't it be great for them to get together again?! I just wonder if they really know just how good they were and how much they are missed.

Positive