As a retailer, I'm both disappointed and annoyed at the progress (or rather lack of it) that Adobe has made with DE and ACS. Today I've discovered that our distributor has switched to ACS v4, which appears to no longer support Adobe Reader 6/7 as it uses .acsm files rather than the older .etd XML format, and Reader 6/7 cannot handle these files. This forces the user to Digital Editions, and here we have major problems - the lack of support for Read Aloud, unable to transfer ebooks to portable devices such as Pocket PC/Windows Mobile and Palm (which was straightforward with Reader 6/7 and the Adobe Reader for Mobile Devices), and as we deal with a lot of companies that don't allow Flash to be installed it's a major headache. And finally, the death knell for Mac OS 10.3.x as DE is no longer supported on this platform.
Why does ACS 4 not support the older Reader versions that could handle ebooks much better than DE? Why is DE's feature set still so very incomplete? When will DE support PDAs other than the Sony PRS-505? (who decided to support only that one and not the others which have a much much larger user base?). Since we started selling Adobe PDF DRM ebooks we have done our best to steer customers away from DE due to all the problems it has. DE has been our #1 support issue, requiring us to spend time trying to solve customer issues that would not have occurred with Reader 7.
Given Adobe's position as the DRM format with the widest range of titles the switch to DE is, in my opinion, Adobe's attempt to get out of the ebook market without making it obvious that they are doing so - if they can make it so that it's too much hassle to bother, then nobody will want PDF ebooks any more and they can release resources that are tied up developing and maintaining the free software to instead concentrate on core products that make them money.
As an employee of a retailer this is obviously of concern to me - if Adobe dump ebooks, then that's 50% of the current commercial catalogue that we sell gone, and leaves Microsoft Reader (which also appears to be left for dead) and eReader (at least they seem to know what they're doing, their copy protection is much simpler and they cover pretty much everyone platform available) as the main ebook formats (I don't count Mobipocket and Kindle - which is also Mobipocket - here because the former has had a lot of issues and the latter is only available direct from Amazon).