Ugh.
The plugin is saving the data like the contributor's name and the contributor questions, it's just that there's a bug in the contributor() helper that you can use to easily get this information.
Data about contributors is saved by the plugin in the tables 'contribution_contributors', 'contribution_contributed_items', 'contribution_contributor_values'. The plugin does not use (or add) the element set that was used by older versions of Contribution, and items contributed with a previous version won't respond to these helpers.
(chaefele: To see the custom contributor metadata on the admin interface, just click the link for the contributor's name)
To temporarily work around the bug in contributor(), you can use a slightly-uglier syntax to get at your data:
$contributor = contribution_get_item_contributor();
$metadata = contributor->getMetadata();
$public = contribution_is_item_public(); // Whether or not the user specified that their contribution could be made public.
echo $contributor->name; // Name
echo $contributor->email; // Email
echo $metadata['My Contributor Question']; // Custom metadata
Alternatively, you could wait for an updated Contribution plugin. The necessary change doesn't affect the data saved by the plugin, it's only a change to the code for that specific helper function.