The folks at Danger applied lessons learned from their original designs and applied it in improving the SK II greatly over the SK I. Major pluses are much better radio sensitivity resulting in a phone and data experience that is best of class. 20% slimmer. Now possible to carry in pocket. Integrated camera with one click picture sending via email. Speaker phone. Controls are all on the outside of the device. No longer need to flip the screen for any functions other than typing on the wonderful, roomy, qwerty keyboard. IM experience second to none. Now support Yahoo as well as AOL. Calendar and Contact synchronization available for a one time charge of $9.95. Perhaps the best thing about the SK II is the effortless, intuitive interface to the various applications on the device. You don't need to have a Computer Science degree to unlock the power of this device. The interface is elegantly simple like Google, Tivo and the Ipod. Rock on.