H2 Database vs SQLite on Android
Things are much better than I have expected. I now have an Android phone (HTC Desire, Android 2.2) and I made a first test.
Opening and closing a database is relatively slow so far (opening an existing database for the second time takes 0.2 seconds, closing about 0.2 seconds), but otherwise it looks like H2 performs quite well on Android, even if the Dalvik VM is not yet as optimized as a desktop JVM. It's too early to give concrete numbers, but Android is now a supported platform.
I would be also very interested in real-world performance tests for the H2 database on Android. I think that H2 will be a lot slower than SQLite, mainly because the virtual machine on Android is still not that great. This got better with Android 2.2, but I think there is still a big difference. My guess is that H2 is currently about 10 times slower. But that's only a guess.
About the Unicode problem: what about converting strings to UTF-8 before storing them in SQLite?