Useful to know that if you pass a string into the construct and the class cannot be instantiated for some reason a SPL LogicException will be thrown. 

This code was ran on a Mac OS X 10.6.7, AMP, PHP 5.3+

<?php

    //  index.php
    try {
        $ReflectedClass = new ReflectionClass('NonExist');
    } catch (LogicException $logicDuh) {
        print_r($logicDuh);
    }
    
?>

Will return a deeply nested array full of useful information about the error.