Instruct: Classify a given Amazon review as either positive or negative.
Query: Disappointing and Dangerous

Xtra shelves appeared to be the answer to a dream--they attach to the corner, in seconds. No tools or hardware are required. I purchased several sets I planned to use them in my bathroom. I even bought extra Xtra shelves to give as Christmas gifts.When I opened the box, however, I found that the promise of magic turned to dismay. Each shelf attaches to the wall with A NAILHEAD, and TWO RAZOR-LIKE BLADES. These metal parts are flimsy, and may work in drywall, but they immediately bend when I try to use them in bathroom paneling.Also, they cannot be used in cabinetry, because they scratch the wood.I could not give them as Christmas gifts, because they cannot be used around children--the blades are too dangerous.They do not go anywhere.I do not recommend them!Thanks,JET