The app seems to add the usual functionality but looks to standardise things such as icon libraries and proports to have found a way to determine screen size/resolution and dynamically adjust the app accordingly. All sounds quite promising.
There are some example apps that use Sencha on the site but initial reports suggest that these are a bit flaky and unreliable. However, they are a positive step in the right direction in making cross-platform apps that look and feel native. Sencha is distributed under the GNU GPL license v3 which is good to hear. Lets keep an eye on Sencha and see what happens.