We haven't visited Apple OS X since Snow Leopard, and while there have been incremental changes, there is nothing radically different in OS X 10.9 Mavericks.
This free upgrade is a roll-up compendium of items Apple has released since the last of the Big Cats OS X versions, Mountain Lion, including significant safety/security updates and features.
Mavericks addresses power savings by putting apps and part of the machine it runs on to partial sleep (called App Nap) under several circumstances. We measured a sampling savings of 19% using Kill A Watt measurements on a solid state MacBook Air, which is significant, especially in locations where power is expensive. Not all apps can or should be put into sleep this way, but Mavericks leaves interrupt-driven apps alone, so there's no "damage" by making them take "power naps."
The last strong version of Apple's Server edition wasn't simple in our opinion. Apple's Xserve hardware — the 1U servers Apple retired — are still supported and indeed the features we found have been simplified and poised towards smaller organizations, or perhaps islands within larger organizations. Apple's Xsan storage devices are still supported as well.
MacOS vs. Windows
There's a danger in thinking that MacOS and Windows should be similar, or even alike. Within the context of larger organizations, MacOS is often a second-class citizen, even now in the third decade of its rivalry with Microsoft. Apple tightly controls its user-focused "experience," which in turn, is coupled to its federated AppleID mechanisms.
Microsoft channels its energies into varying authentication services anchored by its ActiveDirectory and Server Message Block (SMB) protocols. Microsoft has been moving its authentication methods more toward how Apple's works. The reverse is not true and while on the surface Macs seem to be equal players, underneath is a decade of internecine rivalry and the hubris of not-invented-here. Apple champions the user; Microsoft allies business infrastructure; rarely do the twain meet.
Server: Users vs organizations
Connecting Mavericks instances is a foundation of existing Open Directory (LDAP V3 + Kerberos 5) resources, along with Microsoft's SMB2. Apple now eschews SAMBA, which separates it from many versions/distributions of Linux and BSD clients that use SAMBA to run Microsoft's SMB2 and even portions of SMB3.
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