I installed the first shelf per the provided instructions.  It sagged under its own weight.  

My plan was to place a small stereo (3 lbs) on the shelf in a bedroom.  I had already drilled a 3/4" hole through the shelf to allow the cord to pass, or I would have returned the item.  To salvage the project, I mounted a small length of matching quarter round under the unsupported side.  This--while not ideal--made the shelf usable.

The shelf could be a good piece IF the mounting hardware provided attached to the wall on both sides.  (The angles of the protruding rods would obviously have to be different.)  I doubt I will use the second shelf.

Cons: Hardware/mounting method