Moose is the best and easiest way to get closer to real object-oriented programming in Perl. I payed attention to Moose for sometime, and was confused about how to use it until finding "A Gentle Introduction to Moose" on Catalyzed.org (www.catalyzed.org/2009/06/a-gentle-in... which pointed me in the right direction.
Be sure to check out Moose::Manual::Attributes and Moose::Util::TypeConstraints.
I haven't put Moose into use into a production environment yet, or under significant load, so I cannot comment on its performance.
Edit: Still have no performance notes, but I'm loving Moose more and more! It reminds me of this XKCD comic (xkcd.com/353/): programming is fun again.
In my somewhat limited usage of this module, it seems to do exactly what it says on the tin: parse YAML exactly as the spec says, using the most compliant library there is, libyaml. Such adherence to the specification is more than can be said for a lot of library interfaces.
A good step up from Test::More allowing better organization of test files & encapsulation of individual tests. I formerly used Test::Unit, which is incompatible with Test::Builder, so Test::Class is a good find.