One major issue is that Android only supports java 6. All the nice things java 8 brings aren't available. With Kotlin officially supported in Android, you can finally have nice things.
Java on Android is not the same as the latest stable Java from Oracle. Example, there is no complete Java 8 support on Android, only a few things were ported and these are only available on latest versions of Android. The problem is that on Android land people don't/can't upgrade as easily as on iOS, so as a developer you are stuck on Java 6/7.
I don't know about "wrong", per se, but one pet peeve of mine as it relates to Android development is the callbacks system that is ubiquitous in the API. Since functions don't exist in Java except as methods of a class, this means what should be a simple function definition and use of it (e.g. via a pointer) requires at least a class wrapper. It's pointless to have to write it. And this indicative of development in Java, especially for the Android platform, in general.
Others have different opinions of course, and mine is no better than theirs (or vice versa). There are good reasons for the system as implemented, because all such things have trade-offs and a "pros and cons" list. I just don't care for it.