These shelves are extremely sturdy. We keep file boxes on them which weigh at least 20 lb a piece and we have two boxes per shelf. They are very stable and they roll easily when needed. And in my opinion they are nicer looking than those metal storage shelves.  I think they are worth the extra money over the cost of regular metal shelves.

Pros: sturdy, mobile, nice to look at
Cons: somewhat pricey