The 'Order Delivery Date for WooCommerce' plugin, as the name suggests, is primarily a tool that allows ecommerce businesses using WooCommerce to give their customers the luxury of specifying their preferred delivery dates for their orders. The plugin contributes greatly to improving the overall customer experience.

The primary functionality of the plugin revolves around enabling the date field in the checkout form, allowing customers to place an order and simultaneously indicate when they would like the order to be delivered. This feature not only adds a level of convenience for customers but also allows businesses to better manage and organize their order fulfillment process.

But the utility of the plugin doesn't stop there. Beyond the basic function, it is packed with a host of customizable features — these can be adjusted to suit the specific needs of a business. For instance, businesses can set minimum required time for delivery, thereby ensuring they have ample time to process the orders.

Moreover, the plugin allows for disabling delivery for virtual or downloadable products — a feature that is particularly useful for businesses that offer a mix of physical and virtual goods. In the same vein, WooCommerce store owners can also set specific delivery dates for different product categories, ensuring more efficient and logical arrangement of deliveries.

Another feature that speaks to the plugin's robustness and adaptability is that it supports multiple languages — thereby underlining its suitability for businesses operating in diverse markets across the globe.

It is also important to highlight the plugin's compatibility with various themes and plugins. This means that irrespective of the WordPress theme a WooCommerce store owner is using, there is a high chance that the 'Order Delivery Date for WooCommerce' plugin will work seamlessly with it, fostering a harmonious and efficient ecommerce system.