Is Adobe Flash Builder 4.5 good enough for cross platform applications

I am planning to develop a outlook based app for cross platforms(iPhone,blackberry playbook and andriod).I recently heard about the adobe flash builder 4.5.1 update to support these platforms using flex framework and action script. I would like to know the hidden pros and cons of this tool in developing cross platform apps.

Few Queries: Is it compatible with iOS5? Is it giving exact native look across platforms? Is it fast and responsive for touch based events? Can we include any third party sdk's into flash builder project like 3D openGL and external libraries? Does it have all UI Cont开发者_高级运维rols support for all platforms?

Any challenge or hidden disadvantages apart from the above queries are highly appreciated...

Thanks in advance...

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My company is developing cross-platform business apps in Flex and found that the performance is good enough for our purposes. I would imagine an email app would be the same, but if you are trying to do streaming or voice quality, I suspect you might want to write to the hardware layer.

Flex does a pretty good job at supporting native look and feel, but you need to think about/design and structure your app up front (ie. does the gestures in your app design match the feel of those environments). If you don't design for it, it won't happen.

By and large having one code base will reap you large benefits. But if you've not written cross platform applications before (linux/Windows/Unix/Mac, etc), you might find more of a learning curve in your thought process and design process.