Irrelevant until Marco's The Magazine showed us how it's done, Newsstand shows promise as an easily-monetized publishing platform with an audience that is pre-selected for people willing to pay for a quality product.
Unfortunately, since publications are essentially full-blown apps, Newsstand publishing currently requires an extremely unreasonable investment of time and/or money compared with other platforms. Consider that everything in The Magazine could be done with HTML5/CSS and a bit of javascript, but when Newsstand is the platform, you essentially have to write your own display engine, which requires a maintaining a large skill set completely orthogonal to both writing and visual design. Although services exist to allow you to outsource app development, they involve a significant and very un-granular tradeoff between price and control.
Thus, Newsstand remains a very un-democratic platform whose sweet spot for publishers is apparently Objective C programmers who are positioned to source decent writing, and who are able to self-enforce good design/typography.
Feedback mechanisms seem to be another area that hasn't been well thought out in Newsstand (The Magazine included).