Saw a couple odd complaints in reviews. One that it doesn't work, which is simply not true. The person who wrote that was doing something wrong. The other is that it lacks a protective layer of some sort. The original screen didn't have one, so I'm not sure why they would expect it to come with a protective layer the original DS never had. They might mean their stick on bezel/border, but as this matches the color of the DS, and DS's come in all different colors, it can't be expected to come with this product. Anyway, you don't need a new one, you just peel off the original and stick it on your new screen.
As far as the product goes, it gets five stars from me. It cost me $5 total, including shipping, and it works exactly as it did when the original touchscreen was working. I suppose it's a little bit tricky to install, but anyone with a little finesse can manage it. There are some excellent youtube videos up that show the process. This is what I used to do it. Took me about ten minutes to complete the repair, not counting the time it took to watch the video.
Anyway, good product, good price.