Looks like there aren't enough negative mentions yet.
Easy to install and works well. Don't have to worry too much about catching your P3 in the air and getting hit by the props or hitting some one or damaging your props. There's also a string you can install for extra protection.
I would recommend this to a friend
They work as advertised. They probably would help in a crash type situation. Personally, I found the added wind resistance not worth it, and they interfere with the photos and video much more than the propellers do alone. Sturdy product. Easy to install. If you are set on prop guards, buy these. I just found they aren't truly necessary in most situations.
No, I would not recommend this to a friend