Sound quality.
The audio quality from my HTC Desire HD, when plugged into an external amplifier, is significantly better than my iPad. I have heard that the iPhone 5 has made some improvements to this, but I have seen tests that show the audio output levels as being low for driving an amp leading to increased distortion when you have to turn it up to full.
In addition,not here does not seem to be any way of implementing a system wide graphic equaliser, as there is with the Android AnEq app.
Application interoperability
When I open a link in an email to a Facebook page my Android phone gives me a choice of opening this in my web browser or the Facebook app. The iPad forces this to be opened in the web browser - which is slower and uses more data.
This is an example of how iOS prevents applications communicating with each other.
Lack of alternative input devices
There is no predictive keyboard and it doesn't seem possible to use alternatives like Swiftkey.
Screen size
Although the iPhone 5 has a longer screen it is still narrow and oddly proportioned compared to its Android competitors. This presents problems with its use for Satnav in the car. I am not sure if there is even a turn by turn navigation system available for iPhone which can compete with Google Navigation at a reasonable cost.
It is interesting that as I start looking for a phone the HTC One is about £100 less than the iPhone 5, but if obtained as part of a contract over two years the iPhone works put cheaper. This may be how Apple is securing its market share.