The plastic mounting that they attach to is flimsy. Buying on the internet taught me to have a Plan B in case things don't go as planned. Mountings can easily be replaced with inexpensive brackets, or other options. 

Pros: For the money, it is a good deal, the shelves are highly functional and provide shelving above a console/dresser. 
Cons: Minor, just switch out plastic for another type of bracket.