Title image is missing ( but is not the WP 3.5 issue )

you can try this filter

add_filter('wp_get_attachment_image_attributes', 'my_img_title', 10, 2);
function my_img_title($attr, $attachment = null){
    $attr['title'] = get_post($attachment->ID)->post_title;
        return $attr;
}

It should give the the extra title attribute in the img tag.

You can also use the ‘post_thumbnail_html’ filter to edit the html output.

ps: here is a similar question:

Display info from custom fields in all images’ HTML