It is good because as users of old cast iron we get to buy some superb pieces for a lot less money than a comparable Griswold. It is bad because I think the old Wagner and Wagner Ware pieces deserve a little more respect. A Wagner Ware #8 skillet like the one pictured above can be easily purchased for less than twenty five dollars. Mine will cook omelets better than some Teflon-coated sissy pan yet they do seem a bit under appreciated. Maybe there is resentment that Wagner eventually ended up owning Griswold right around the time the quality of both brands went sharply downhill?
The name "Wagner" did not appear on skillets after 1922. When you find one like this #10 shown above you are looking at an old piece. The Sidney, O. stands for Sidney Ohio. The Chicken Fryer, lid and the #8 skillet were probably cast in the 1940s.
The Wagner Manufacturing Company was founded in Sidney OH in 1891. It became one of the two largest makers of cast iron cookware along with Griswold and continued to be a family owned company until the mid 1950s. After being sold to the Randall Company, Griswold was also acquired in 1957 (you can find pieces with both markings). In the years that followed a series of transactions took place that ended up seeing the Sidney foundry close in 2000.
Lehman's is currently selling a Wagner Ware 3 skillet set that they report as being "USA made". I have not seen these pieces nor do I know where the foundry is located. It is possible that these skillets were cast prior to the closure of the Sidney OH foundry and are now being "finished" here.
Some production has occurred in China since the Sidney OH foundry closed.