My favorite feature would have to be the clean up of the OO layer. It's going to make my life a lot easier.

I'm also looking forward to:

• Parrot - because I like multi-language programming.
• PRE/POST/wrap - because they look like they will let me write design-by-contract code easily.
• macros - because domain specific languages rock and source filters are evil.
• the type system - I like compile time errors. I like the code to document itself.
• function "style" - things like lazy lists and simple currying making it easier for me to code in a functional style if I want.
• it still looks like perl5 - I can still write a quick'n'dirty script if I need to.

Actually, I'm looking forward to pretty much everything I've heard about perl6 ;-)