RIM has done a pretty good job of translating its Windows software to Mac, removing most of the bloat but maintaining the same core functionality. The UI is super simple, and, unlike on DM for Windows, the main options aren't hidden behind unnecessary menus and sections. The main functions (backup and restore, information syncing) are clearly marked and work exactly how they should. We're big fans of Google Sync, so we don't have much use for the calendar and contacts backup, but the notes and tasks syncing are both useful to have.
Additionally, the functionality from BlackBerry Media Sync has been integrated into Desktop Manager, further proving that this isn't just a one trick pony. Unlike certain other smartphones, the BlackBerry doesn't actually show up in iTunes, but you can choose certain playlists that will sync up to the device -- as long as it's not DRM protected. It's a solid integration and will be more than sufficient for most people.
Backup and restore work pretty much as you'd expect them to, and there's nothing revolutionary in that regard. We like how you can still selectively back up certain databases (BlackBerry Messenger contacts anyone?) if you don't need a full backup, and you can also selectively replace certain databases just like you can on a PC. The one major difference between the Mac and PC versions of the software is the firmware upgrade process. At this point, installing non-official OSs from a Mac is a no go. Unlike on the PC, you don't install the installer and then get prompted for the upgrade. Instead, the software connects to RIMs servers and checks for software updates that way, only allowing you to install OS builds that RIM explicitly says you can. We're sure some crafty users will figure out a workaround in due time, but for now, if you want to load an unofficial OS, you'll have to go back to the PC version.
In the end, Desktop Manager for Mac is a necessity for anyone with a Mac and a BlackBerry. We can't even begin to say how grateful we are that RIM has finally decided to pay some attention to the sizable number of non-PC users that have been stuck with poor alternatives for way too long. It's taken long enough, but at least the guys in Waterloo managed to do it right.