
Shippo's UPS rates are considerably better than what I can access through WooCommerce or my own UPS account. The interface is smooth and reliable. Unlike some competitors, there's no monthly fee for using this service (though a premium subscription would entail a fee). Connecting to WooCommerce and eBay is very simple. Review collected by and hosted on G2.com.
My biggest dislike is really a feature request: I wish I could display live rates at checkout in a WooCommerce store. As it is, I wind up refunding customers for the overage they pay in shipping, as we don't want to make money on shipping.
Additionally, it would be nice to integrate more tightly with WooCommerce's order notification system, sending tracking info as part of the Order Complete email instead of as a separate email from Shippo. Review collected by and hosted on G2.com.