Choosing Java vs Python on Google App Engine

Question

Currently, Google App Engine supports both Python & Java. Java support is less mature. However, Java seems to have a longer list of libraries and especially support for Java bytecode regardless of the languages used to write that code. Which language will give better performance and more power? Please advise. Thank you!

Edit: http://groups.google.com/group/google-appengine-java/web/will-it-play-in-app-engine?pli=1

Edit: By "power" I mean better expandability and inclusion of available libraries outside the framework. Python allows only pure Python libraries, though.

Answer 1

By now, both Python and Java's implementations are reasonably mature and solid, and their functionalities are quite 

 the same (I don't think it's quite 100% equal yet, but moving in that direction). So, if you already have knowledge of any one of these two languages, you should just go for it.

And if you are a beginner or one who does not know either of them and want to try the non-Java languages that are (more or less;-) supported on the JVM side of GAE ( This includes Scala, server-side Javascript, JRuby, etc), then it's worth trying.

If you prefer a complete development environment including IDE support => Java

If you need the most advanced features of App Engine => Python