Months ago on Hypercritical [1], John Siracusa had a series of episodes where he was talking about weaknesses of programming in Objective C vs more dynamic runtimes like C#/Java, like garbage collection, dynamic typing, etc.
One of the advantages he cited & partially dismissed, though, was that since Objective C compiles directly onto the hardware, performance & battery life is better on ram- and cpu-limited phones compared to the added overhead of Dalvik or another virtual machine or JIT. (His theory was that that bought them time in the short term but is still a long term issue for Apple; I'm not sure I agree, but don't disagree Apple needs to be evaluating this stuff.)
[1]: http://5by5.tv/hypercritical/14