I have used interparcel for many years (7+) and generally they are very good. Booking a delivery is easy. Your choice of delivery service will determine the service you get after that. Tracking information is usually accurate and easy to obtain. However like insurance, the proof is often in how things are dealt with if they go wrong. In this regard I would say interparcel are average. When you book via a shipping agent like interparcel your claim for a missing damaged item has to go via them to be processed so it will be slower than going direct to the delivery company itself.