I'll explain my development strategy, why I chose PhoneGap, and what I've learnt along the way.
If you decide today that you want to create a mobile application, you have to decide on a development strategy - especially if you want to target multiple platforms.You can either learn to program from scratch for each platform or you can use a framework that abstracts on top of all of the platforms and reuses your existing web development knowledge - like Apache PhoneGap. If you decide to use PhoneGap, you still have figure out whether to use a library specially designed for mobile applications - like Sencha or jQuery mobile - or use general libraries like Zepto or jQuery. There are a lot of decisions to make, and there's no one best strategy at this point in the game.