I am happy with these shelves. I purchased 6 of them and they  all came in great condition. They seem sturdy, and don’t slope down. A couple of them seem to slope a little upwards actually… not by much though and i think its possible over time they will likely fall more flat.  I did drill a hole in a few of the metal brackets so they could be attached to wood beams.  I also purchased my own hardware, just to be sure I was using good sturdy hardware.  Though will say what came with the package looked pretty good as well.   I think the shelves were a great buy and would purchase again.