Have you looked at the games in the Showcase section of this site? http://www.java-gaming.org/boards/showcase/2/view.html
Also, check out http://www.jagex.com/
Pros: Java is very fast, rivals C. But if you want to focus on a specific platform(s) you do have the option of programming the bulk in Java and then embedding key customized components written in C or whatever native language. There is a lot of support for scripting languages as well. Java's Jython code executes faster than Python, I hear. Java has a big community, lots of helpful people. Some excellent IDE choices. And the price is right.
Cons: mixed reputation in the gaming world, not available so much on consoles, not as much market penetration as Flash, though still respectible. If you are just learning it, there are some significant conceptual hurdles and technical hurdles. There's a lot of "I just want to do X" but you have to learn to handle the simple thing you want to do as part of a more generalized, more complicated framework. Seems to be easy for people to lose patience and say/think the language is bad or slow when the problem is in their understanding. Lots of handwringing about Java's mismanagement and imminent doom. (Check the TIOBE site to get a perspective on that one.http://www.tiobe.com/index.php/content/paperinfo/tpci/index.html