“What is the uplift to take a mid-level J2EE developer to become an Android developer? Are development environments similar and the APIs like enough to make the leap without a large learning curve? “
I would say that if you know
Java very well the learning curve is pretty shallow. At work one very senior Java developer was able to make a very sophisticated Android Video player, with no previous Android experience, in a couple of weeks. He also made several other Android apps including a mapping application. He might be an exception but other Java developers at my work usually stumble with security permissions, the Android intent model, and a few other items but then quickly become productive.
“I know the interaction with serial devices at the desktop level can be pain (such as a GPS,) is the interaction/integration easier on the Android? “
Not 100% if you are asking about how hard is it to work with sensors such as GPS from Android or how hard it is to use sensors via a desktop and the Android emulator. If you just mean how hard is it to access sensors from Android I would say it is pretty trivial.
