I have recently had the pleasure of diving head first into some Android development. Putting asing my feelings about Java, and unnecessary nomenclature obfuscation of well-known, long pre-existing paradigms (e.g. Intent vs Message, Activity vs Window/Dialog), I have been quite impressed..
However, the security model gets annoying and seemingly really really limits the scope of applications and services that could be provided by 3rd party developers. There are newish paradigms like Device Administration Application, but the support and the feature set still leaves a lot to be desired.
Overall, my sense is that Benjamin Franklin would not approve of the Android security model and I kind of agree.
"They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety."