Test::Class is very good, but you probably want to check the more recent Test::Routine.
It is based on Moose, has a Moose-based interface which makes it nicer to handle for Moose users, and it allows roles compositions for tests, which can make a significant difference.
It also has a good tutorial : Test::Routine::Manual::Demo.
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.
An excellent tool for testing complex object-oriented code, especially where inheritance is in use.
The interface is based on the well-known xUnit style and will be reasonably familiar to programmers who have used jUnit, and similar tools. Test::Class mixes very nicely with non-xUnit tests so you do have to choose one way or the other.
I can't say enough good things about this module. Inherited tests, loading all of your classes once and only once (a nice little performance boost compared to multiple .t tests) and great documentation.
Also, if you have a large object-oriented hierarchy of code, Test::Class does an excellent job of allowing your test organization to match your code organization. No more staring at a long list of .t files and wondering which one has the code you want to test. Just check the corresponding test class for the code you're concerned about.
Test::Class keeps getting better. Especially in 0.14, the ability to run specific tests via the TEST_METHOD environment variable is very useful. I use it extensively throughout my testing code. Thanks for a very perl-y OO test module.