UI5 is special because it allows the Mobile developer to develop cross-platform apps for multiple platforms. However usually these platforms are just consumer devices, what happens when you want to deploy your apps onto rugged devices ?
Option 1: Use a HTML5 compatable browser and UI5 as a web app.
Option 2: Use Cordiva and enclose your UI5 into an app.
However when you look at the Rugged device market, most of the devices still only run Windows Mobile 6.x which is useless for HTML5 apps and not supported by Cordova.
The answer is to use one of the many Rugged Android devices coming onto the market. see here for a list of devices I survey: http://scn.sap.com/docs/DOC-53938
So before you invest in a one-drop latest shiny device, consider your workforce, consider rugged.
Rugged Android Device + UI5 + Cordova = Mobile worker App's with offline, rugged capability.