Loop help with nested categories

Quick Q.. (i hope)..

I’ve got several nested categories from which i am including several (but not all) child categories as a “What’s New” section of my site. I’m trying to have it write a <p> tag prior to each loop, based on the child category.

Here’s what i’ve been trying to do:

<?php query_posts /* enter # of posts here----> */('showposts=3&cat=15,27,28,29');/* For a full list of possible arguments you can pass to query_posts see http://codex.ww.wp.xz.cn/Template_Tags/query_posts */

global $more;    // Declare global $more (before the loop).
$more = 0;       // Set (inside the loop) to display content above the more tag.

?>

<ul>
<?php while ( have_posts() ) : the_post(); ?>
<li>
<?php if (is_category('15')) { ?>
<p class="category_leadin">Article Review:</p>

<?php } elseif (is_category('27')) { ?>
<p class="category_leadin">Book Review:</p>

<?php } elseif (is_category('28')) { ?>
<p class="category_leadin">Video Review:</p>

<?php } elseif (is_category('29')) { ?>
<p class="category_leadin">Website Review:</p>

<?php } else { ?>

<?php } ?>
<a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a><br />
<?php the_content('Read more...'); ?>
</li>
<?php endwhile; ?>
</ul>

This is how it should ideally output:

Category name
Title/link
Content
Read more…

[repeat loop]

Problem is, its only returning the parent category (in this case “Reviews”), and not the child category )ex: “book reviews,” or “Site reviews.”

Does this make sense? Can anyone help me sort this out?

Thanks in advance for any insight you can offer.