Fewer queries
Instead of doing a separate query for each taxonomy, the plugin now does a single combined query, using a proposed API.
Custom Post Type Support
Custom post types go very well with custom taxonomies, so the Taxonomy Drill-Down widget now has a post type dropdown.
Correct Template
This version doesn’t mess with category and tag templates anymore. In earlier versions, when you would go to /category/example, it would attempt to load the multitax.php template file, instead of category.php etc.