Quite good (and lengthy) chapter worth of weekend reading for mobile development
Aral Balkan, the author,  describes many important  concerns or considerations before you start mobile development :
http://mobile.smashingmagazine.com/2012/06/18/mobile-considerations-in-user-experience-design-web-or-native/

My favourites quotes from the article:
If your choice of platforms and technologies is based simply on your perceived short-term business needs or on the current competencies of your team, then you are making a decision that solves your own problems, not the user’s problems. This may have short-term advantages, but you will not be able to compete in the long term with those who solve the user’s problems first. Your choice of technologies and platforms should be based on how best you can meet the user’s needs, not on ideological bias or on obtaining short-term gain at the risk of long-term loss.

A common mistake I see many designers make is to assume that by using cross-platform authoring technologies they will be able to write once, run anywhere. This is a myth. And acting on the myth can lead to rather costly underestimations. Your application might run on multiple platforms, but this rarely—if ever—means that it will run well on multiple platforms.

Designers who do not take the unique cultures, customs, language and norms of their respective platforms into consideration risk making their applications look and sound out of place. The applications will appear noticeably foreign, unnecessarily loud and usually rather arrogant, simply because they are culturally insensitive.

The worst thing you could do, of course, is disrespect all of your users by creating a lowest-common-denominator application that gives every user on every platform an unoptimized user experience. At that point, you would be at your most vulnerable.

Supporting multiple platforms is not a feature unless you can support them all well. You may have first-to-market advantage, but that will last only until you are outdone by your best-in-market competitor.

So, write once, run anywhere is a dangerous myth. Cross-platform applications that compete successfully are write once, optimize everywhere. You must understand the implications this will have on your budget and schedule and plan for optimizing, testing and supporting your application on every platform you choose to support.

In summary, be careful when creating native binaries that simply wrap applications that do not use native components. These apps have a tendency to look like native applications, but they cannot behave like native applications because they do not use native components in native frameworks. A PhoneGap application that uses the jQTouch framework might display what looks like an iOS table view when running on an iPhone, but this is simply an HTML look alike brought to life by clever use of CSS and JavaScript. It pretends to be an iOS table view, but it cannot meet the behavioral characteristics of a real table view component from the Cocoa Touch framework, and thus it ends up creating expectations that it cannot meet.

The advantages of building native applications using native technologies are numerous. For one thing, you have complete flexibility in optimizing the application and user experience. When you use native components and adhere to the human interface guidelines for your chosen platform, your application will conform to the culture, language and norms of that platform. It will be easier for users to learn and use.