And more importantly, why is this on the App Store if it's HTML5? I'd like to see this running 100% in the browser and then compare vs. native app.
Having said that, the bigger question is: why do all that custom work when you can make a native one much quicker and more easily?
I think what this app shows is the lack of a HTML5 framework to quickly put together mobile apps that feel native the way you can with the iOS SDK or Android SDK. In the HTML5 world there are a lot of frameworks and libraries to create a mobile website, but there isn't one that lets you make a native-feeling web app. There are a lot of disparate pieces addressing different issues (PhoneGap/Titanium for native app launching, Bootstrap/Foundation for UI controls, fastclick implementation for faster tap response times, removing the URL header, hiding browser scroll bars, ...).