Originally Posted by DArtagnan 
Please provide both proof and an objective definition of "efficient mobile OS".
Efficiency as in the number of CPU cycles and resident memory needed to accomplish a task. A great example is the scrolling, in which the heavy use of Javascript for user interfaces on Android - bytecode will ALWAYS be slower than native compiled code. Always. Period.
Here is the classic example:
https://plus.google.com/100838276097…ts/VDkV9XaJRGS
What I am NOT talking about is the subjective 'user experience'. I personally love Android and use it as my main phone. BTW … the Galaxy S2 is growing on me in spite of the quirks remaining … but I still would choose the Droid 4 ten times out of ten