I have just come across cocos2d-x and I have say it looks great. I have been developing Android project for while now. I had no problem getting the sample application up and running, but when I came to extend it, the first thing I noticed is that it does not appear to resume properly, all I get is a black screen after screen unlock or switching back to it.
This has something to do with the OpenGL context being lost I think.
Other people (including me) have this problem too This thread may help: http://www.cocos2d-x.org/boards/6/topics/27903