3 different operating systems, 3 separate languages and development environments, and counting. To be able to cater to all of these operating systems natively, mobile app developers need to have someone able to be an expert in each of these programming languages and also be an expert in the nuances of how each mobile operating system works. Task lifecycles, multi-threading, memory limitations, garbage collection, etc.
Thus to have 1 app developed in its native language and environment will take 3 times as long. Thus tripling the cost of development.
This quick read does a fantastic job listing the strengths and weaknesses of these two popular platforms. I walked away from the article with a better understanding of the platforms and even a general overview of the architecture involved in the development.
The closing argument for utilizing Xamarin for larger projects was very sound and a point not often encountered in comparison articles. I am looking to run a couple small apps to gain some first hand experience on them; but with the size of the projects and the possibility for growth the choice for now seams clear.