Works very well. Was able to use this to convert Nokia Lumia 1020's .DNG raw files to a format that the current version of Mac OS X and iPhoto can actually use. If your camera is on the list of supported devices, this will probably work for you.
Anyone who is familiar with Photoshop's Batch dialog or other mass-convert utilities will probably get along just fine with the interface. It's not as simple as something developed by Apple, but it gets the job done.
Mac OS X 10.9.1
Digital Camera RAW Compatibility Update 5.03
Nokia Lumia 1020 running Nokia Black / GDR3
In preferences, set Compatibility to "Camera Raw 4.6 and later" (this was the newest version to work in OSX/iPhoto)