What does this module provide versus just setting up APC

You can use APC as a cache bin, as suggested in the documentation.

When
the memory allocated by APC is big enough to cache the entire drupal
cache (to do so check the size of the cache_% tables in the database when
the cache is hot) you can use Step2b, if not use step 2a.

- Step 2a
Add the following code to your settings.php file:

/**
* Add APC Caching.
*/
$conf['cache_backends'][] = 'sites/all/modules/apc/drupal_apc_cache.inc';
$conf['cache_class_cache'] = 'DrupalAPCCache';
$conf['cache_class_cache_bootstrap'] = 'DrupalAPCCache';
//$conf['apc_show_debug'] = TRUE; // Remove the slashes to use debug mode.

- Step 2b
Add the following code to your settings.php file:

/**
* Add APC Caching.
*/
$conf['cache_backends'][] = 'sites/all/modules/apc/drupal_apc_cache.inc';
$conf['cache_default_class'] = 'DrupalAPCCache';
//$conf['apc_show_debug'] = TRUE; // Remove the slashes to use debug mode.

Local tests show up to 12% speed increase using "Step 2a".