I had previously used firewood racks liked this one, but shorter (4' or 8') and had them standing on a concrete floor or backed against a concrete wall. I bought two of these in order to stack a cord of wood outside on the far side of my driveway. When I had the first rack just about full, it tipped over and dumped the load. The second time, I made sure the rack was perfectly level before I gegan and worked slowly, using a level to make sure I kept the load even. Even so, just as I finished filling the rack, the load shifted and the rack tipped over. The third time, I moved the rack over to an area where it was backed up against some trees and put boards under the front legs to keep them from sinking under the load. This worked. 

Pros: Sturdy, easy to assemble, cover is a good feature for outdoor use.
Cons: Too unstable to be used out in the open; needs to go against a wall.