nick_nielsen on "Custom post types, taxonomy in shortcode problems"

I'm trying to make a short code that prints out a glimpse of all the custom post types in a custom taxonomy. As far as I can make out it should work, but it doesn't.
I'm not a programmer and this has been put together trawling the web, forums and the codex.
It could be I've made a spelling mistake or missed a comma - but I can't find the mistake.

function wg_album($wguse){
	extract(shortcode_atts(
		array('use' => 'work'), $wguse));
	$args = array(
  			'post_type'   => 'work_gallery',
			  'tax_query' => array(
					array(
						'taxonomy' => 'use',
						'field' => 'slug',
						'terms' => $wguse
					)
				)
			);
	$workpages = new WP_query($args);
	ob_start(); ?>
		<ul class="work-pages">
	<?php foreach ($workpages as $wpage) { ?>

			<li>
				<a href="<?php echo get_page_link( $wpage->ID ); //the permalink?>">

					<?php echo get_the_post_thumbnail($wpage->ID)//the featured image?>
					<h3><?php echo $wpage -> post_title ; ?></h3>

				<p> <?php echo $wpage -> post_excerpt ; ?></p>
				</a>
			</li>

	<?php } ?>
		</ul>
<?php
	return ob_get_clean();
}

Please help