I have a session oriented protocol that I originally built on top of MINA
that I recently ported over to Netty. I have the client portion running in
an Android application.
I can tell you of a number of issues I've had:
1) NIO is/was broken in Harmony. It leaks file handles and eventually
crashes our app. We are building the Android framework/kernel so we ended up
patching our local source tree to fix this since the fix apparently didn't
make it in until gingerbread and we are building for 2.1
2) SSL is broken in Harmony. We cannot do server authentication because of a
bug that causes the SSLEngine to incorrectly complain about a valid usage of
the certificate with respect to the extended usage flags. The only way we've
been able to use the SSL handler in Netty is to force the connection to
anonymous authentication with DH key exchange.
Other than that, things have pretty much worked as expected.