Making a new view (master only) that receive the UID as contextual filter and the Views Field View module there is a good possibility of retrieving information about the contents of an specific user that using the normal relationships (the ones built-in Views) won't allow you to do or will give you issues with MySQL and sometimes Ajax request.
Example of embeddable view to retrieve count of authored content of an specific user:
$view = new view();
$view->name = 'ctn';
$view->description = '';
$view->tag = 'default';
$view->base_table = 'node';
$view->human_name = 'ctn';
$view->core = 7;
$view->api_version = '3.0';
$view->disabled = FALSE; /* Edit this to true to make a default view disabled initially */
/* Display: Master */
$handler = $view->new_display('default', 'Master', 'default');
$handler->display->display_options['use_more_always'] = FALSE;
$handler->display->display_options['use_more_text'] = 'más';
$handler->display->display_options['group_by'] = TRUE;
$handler->display->display_options['access']['type'] = 'perm';
$handler->display->display_options['cache']['type'] = 'none';
$handler->display->display_options['query']['type'] = 'views_query';
$handler->display->display_options['exposed_form']['type'] = 'basic';
$handler->display->display_options['exposed_form']['options']['submit_button'] = 'Aplicar';
$handler->display->display_options['exposed_form']['options']['reset_button_label'] = 'Reiniciar';
$handler->display->display_options['exposed_form']['options']['exposed_sorts_label'] = 'Ordenar por';
$handler->display->display_options['exposed_form']['options']['sort_asc_label'] = 'Ascendente';
$handler->display->display_options['pager']['type'] = 'none';
$handler->display->display_options['pager']['options']['offset'] = '0';
$handler->display->display_options['style_plugin'] = 'default';
$handler->display->display_options['style_options']['default_row_class'] = FALSE;
$handler->display->display_options['style_options']['row_class_special'] = FALSE;
$handler->display->display_options['row_plugin'] = 'fields';
$handler->display->display_options['row_options']['default_field_elements'] = FALSE;
/* Campo: COUNT(Contenido: uid del autor) */
$handler->display->display_options['fields']['uid']['id'] = 'uid';
$handler->display->display_options['fields']['uid']['table'] = 'node';
$handler->display->display_options['fields']['uid']['field'] = 'uid';
$handler->display->display_options['fields']['uid']['group_type'] = 'count';
$handler->display->display_options['fields']['uid']['label'] = '';
$handler->display->display_options['fields']['uid']['alter']['trim_whitespace'] = TRUE;
$handler->display->display_options['fields']['uid']['alter']['strip_tags'] = TRUE;
$handler->display->display_options['fields']['uid']['element_label_colon'] = FALSE;
/* Filtro contextual: Contenido: uid del autor */
$handler->display->display_options['arguments']['uid']['id'] = 'uid';
$handler->display->display_options['arguments']['uid']['table'] = 'node';
$handler->display->display_options['arguments']['uid']['field'] = 'uid';
$handler->display->display_options['arguments']['uid']['exception']['title'] = 'Todo(s)';
$handler->display->display_options['arguments']['uid']['default_argument_type'] = 'fixed';
$handler->display->display_options['arguments']['uid']['summary']['number_of_records'] = '0';
$handler->display->display_options['arguments']['uid']['summary']['format'] = 'default_summary';
$handler->display->display_options['arguments']['uid']['summary_options']['items_per_page'] = '25';
/* Criterios de filtrado: Contenido: Publicado */
$handler->display->display_options['filters']['status']['id'] = 'status';
$handler->display->display_options['filters']['status']['table'] = 'node';
$handler->display->display_options['filters']['status']['field'] = 'status';
$handler->display->display_options['filters']['status']['value'] = 1;
$handler->display->display_options['filters']['status']['group'] = 1;
$handler->display->display_options['filters']['status']['expose']['operator'] = FALSE;
$translatables['ctn'] = array(
t('Master'),
t('más'),
t('Aplicar'),
t('Reiniciar'),
t('Ordenar por'),
t('Ascendente'),
t('Desc'),
t('Todo(s)'),
);
Nota: remember to check the content types and the translated strings.