Not sturdy. Very ineffective way of mounting it to the wall. The "brackets" on the shelves are just like little sockets that you put the screw head in and then move down so it "locks" in place. Only problem is that the piece on the shelf that is "locking" over the screw head is super thin and cheap mdf board, not solid wood, so it easily gives way. 

Once this happens, the entire integrity of the shelf is compromised.

They're cheap and they look fine but I would spend more money to get better shelves that use solid wood.

Also, they are very very narrow/shallow. You can't fit even small books on it. Only can be used for very small (and light) items.