I love that you can create unlimited products & categories, it's easy for both new users as well experienced ones! The best thing about this software is its price (free) which makes me continue using my website even after some time has passed since i was first introduced in converting cart into webstore.
There are no downsides at all!! You should try out Convercart if your looking forward to have an ecommerce application like Shopify or WooCommerce but want something free of charge :) We use convercatr to help us manage our inventory system by creating product listings from various sources such as Google Shopping results etc., we also utilize it when dealing with clients who do not yet own any physical stores/website - allowing them sell through one click only without having to worry too much over stock management while still being able to track sales statistics back easily.