Most people that slag Vista on Slashdot do it because of its problems for home use (DRM issues and the like). I agree that implementing Vista in a business environment is problematic - as enterprise architect for the world's largest company in my industry segment, I do have some experience in that area - but upgrading to Vista from XP or Win2000 in a corporate environment involves the same due diligence (app compat testing, driver research, hardware upgrades, etc) as did upgrades to previous upgrades of Windows. A lot of companies upgraded directly from Win95 to XP, and I can guarantee you that they found that XP did not perform acceptably on a 64Mb Pentium-100, and that some applications did not survive the upgrade.
Some poorly-written applications may not work properly on Vista, but that has always been the case. If third-party developers always followed Windows guidelines, Windows wouldn't have to be such a steaming pile of compatibility hacks. But the fact remains that those applications have to be supported - can you imagine what Windows threads on Slashdot would look like if they weren't? - and any new version of Windows that adds significant functionality will break some subset of the Windows application base. Vista does add significant functionality - it natively supports x64 processors, moved most device drivers from kernel mode to user mode to increase stability, has TPM and Bitlocker support (both important for enterprise usage), supports regulation of content on removable drives, etc.
Whether you think it's worth it or not is one issue - whether it's objectively a step backward is another. Complaining because it makes enterprise upgrades difficult is irrelevant; enterprise upgrades are always difficult. If this stuff were easy, many of us would be out of a job.