<?php echo get_post_meta($post->ID, 'value', true); ?>
if isset ($value) {
<p>
<?php echo get_post_meta($post->ID, 'value', true); ?>
</p>
}
if(get_post_meta($post->ID, 'value', true)) echo get_post_meta($post->ID, 'value', true);
if( ! empty( get_post_meta( $post->ID, 'value', true ) ) ) {
echo get_post_meta($post->ID, 'value', true);
}
if( ! empty( trim( get_post_meta( $post->ID, 'value', true ) ) ) ) {
echo get_post_meta($post->ID, 'value', true);
}