Starting android development is easy thing. Normally developer are fully aware about java language. It makes easy to learn and develop android application. Because of its open source nature so many tutorial are available on internet. after so many thing android development is pain for developer in comparison of iPhone development in some cases
1) Device resolution and densities : In android thousand of android device available with different kind of densities and resolution.
see this picture. A developer can imagine the pain to make one application that runs perfectly in all. That's impossible.But if you see iPhone, its has only two densities iPhone or iPod And iPad
2)Its hard to earn with android : on Google play, there are so many of crap application are present.In iPhone, quality of application are much more better than android. Because of manner of uploading in android, its easy to upload application. I have seen android hello world application on Google market. that make hard to get notice