Ajiao, thanks for passing the link along. It certianly could have been used to make the code in the loop a bit easier. For example, you could use the plugin to condense the following lines down to a single line:
<div class="thumb">
<?php if(get_post_custom_values('thumbpic')) : ?>
<img src="<?php echo get_post_meta($post->ID, 'thumbpic', true); ?>" />
<?php endif; ?>
</div>
Underneath, the plugin is essentially doing the same as the above code. However, I would probably consider the plugin if you were going to do this sort of change in multiple places on your site.
The workflow for creating articles (adding thumnails, creating a custom field, and creating an excerpt) would be the same with either approach.
