Well i am a mobile game/app developer so i know few things about this.
1. Symbian is OS, and you can run native applications written in C++ / Python on it. these applications canm directly access OS functions, giving ultimate speed.
2. Symbian supports running multiple applications at a time, which is not supported by many other phone OS.
3. Since symbian applications can access OS directly, there also have virus for phones.
4. Java applications don't access OS directly, instead they have, Java Runtimes as middle level.
5. Java applications are ALWAYS slower than native applications.
But this all doesn't mean Java are not as much fun as native. In fact only Nokia Series 60 are major player in symbian. While almost every phone supports Java. So there are lot more games for Java than Symbian.
Linear Mode
