D. Emerson Eddy has written a thorough examination of one of my favorite comics series, the late 80's Shadow series by Chaykin, Andy Helfer, Bill Sinkiewicz, and Kyle Baker. I am especially a fan of the Helfer/Baker issues; I thought those were just amazing examples of high adventure wedded with black-as-ink comedy. To this day I would give mucho dinero for a four-issue miniseries featuring the Shadow's "Cob Driva" Percy Jenifah.
However, at the end I think D. has erred somewhat: the cancellation of this series, by most accounts, was requested by Conde Nast well before the final issue of the series, #19, not because of what H & B did in that particular issue, but because of the total incongruence of what was going on in the comic with the established Shadow character that would soon be featured in the movie which was surely then in the planning stages. And while it may have been a little too over-the-top in its superhero parodics, I think more substantial plot devices were on the way (the rock star who paid to have the Shadow's girasol stolen), so I think that this issue stands out a bit more because of the abrupt cancellation directly afterwards, and wasn't necessarily indicative of any potential direction or downward slide.
The article, should you choose to read it, is in Adobe PDF format; which means if you don't have Adobe Reader then you'll need to go to Adobe.com and download it...but worry not; it's free.