In order to have your features presented with linebreaks you should use "nl2br".
At your theme folder, on your "product.tpl" file, replace
<li><span>{$feature.name|escape:'htmlall':'UTF-8'}</span> {$feature.value|escape:'htmlall':'UTF-8'}</li>
with
<li><span>{$feature.name|escape:'htmlall':'UTF-8'}</span> {nl2br($feature.value|escape:'htmlall':'UTF-8')}</li>