The Foundry edition ruined Medieval Warfare imo. This was a risk that Terry Gore took, and it didn't pay off in the sense that not only weren't the rules popularized, they also werent' completed. Despite a huge rule book, practically all Eastern armies are missing, so you can't do say, the Crusades from it. Very sad.
The rules themselves are still quite good--WRG 6th Ed. heavily modified. Imo they are dramatically better rules than say, FoG turned out to be, but there are also quite a few faster playing alternatives out there these days. Impetus, Hail Caesar, various WAB replacements, lots of options.
As a general rule the only time I see Terry's rules played is when I pull them out and GM them. This is quite a shame as there are great dynamics within those rules, and they tend to work very much like you would expect an actual medieval battle to play out (Terry was a history professor, after all….). However given the number of current good options, and the current holder of the rights (Foundry), I don't see them coming back in a big way. Just not going to happen. I would happily play a game or two of this, or his sister set, Ancient Warfare (naming things was not Terry's strength, apparently), but Ancients/Medievals in general is not a common interest with my club, and a fringe rules set of an uncommonly played period just doesn't see a lot of light of day.
Shan