New features like Address Book Server and Mobile Access Server help out both users and administrators
Home directory syncing is much improved
Price has been cut in half, and there’s only one version to buy
Push services for email and iCal, a better server-side email rules UI, and email meeting invitations for iCal server
Improvements to OS plumbing help services scale much better
Cons
For non-Apple clients, using iCal and Address Book servers will not be as consistent of an experience due to other platforms lagging Apple’s level of support for CalDAV and CardDAV standards
For companies with a mix of PPC and Intel servers, upgrades could become complicated due to Mac OS X 10.6 Server being Intel-only
Limited in-house customization available for Address Book Server services