Valuable Features:
* HTML5 app platform using standard web technologies.
* PhoneGap is basically a native wrapper of a web app.
* Provides a bridge between JavaScript and native device APIs, meaning that a web app written in javascript will have the ability to access your device's native features such as camera, push notification, storage, contacts, mail clients, and many other native functions.
* Binding a web app with a PhoneGap has an advantage of distributing your app like a native app on mobile app stores (iOS app store, google play, windows marketplace, etc.).
* Free open source framework which was recently acquired by adobe, so there is no chance of you having to pay for it.
* API documentation is well maintained with a self explanatory sample code.
* Single code base for all platforms (cross-device compatibility), meaning you have to write an application just once and most of the code is shared between different platforms (iOS, Android, WebOS, BlackBerry OS 6.0+, BlackBerry OS 5.x, WP7, Symbian, Bada).
* Plugin support on github for various platforms, the plugin works like addons. This means that if you want a specific feature on a platform you can add the related plugin and start using it right away. There is no need to start from scratch.
* Strongly event-driven.
Room for Improvement:
* Look and feel are not the same as a native app.
* Performance is not good, especially if the application is loaded with graphics. However, you can implement caching or native graphics acceleration, but still, performance wise, a native app wins.
* Lack of pre-built UI widgets, transitions, and standard controls.
* Page transition and 3D animation run slower as the GPU usage depends on the web browser running the web app.
* Portability support is limited, especially for BlackBerry.
* In order to integrate platform specific plugin's, you will need the SDK installed for the respective platform.
Other Advice:
I am a mobile application developer. For me, PhoneGap happens to be quite useful as I can share my existing code (javascript code) on different platforms, and I therefore do not have to do the same thing on different platforms. Plus with PhoneGap, I can sell my web app easily on different app stores.