I've only gotten the one order from them this spring, and I must say the ducklings looked a lot healthier and livelier than I expected after spending 48 hours in a box going cross country in the belly of a plane. I paid the little bit extra for the "grow-gel" to be put in the box, and whatever was in the tray was completely gone when they arrived, but since its some kind of nutrient gel (probably just basically the equivalent of unflavored gatorade congealed with agar or some other food starch) and is mostly water, it no doubt help them.
From what I gather, Metzer's has a reputation as being among the top tier of mail order hatcheries in terms of quality and customer service. Due to the very nature of the business, no doubt there are problems with shipments being lost, cooked, chilled to death, etc., by the USPS and Fed Ex (who transports under contract most of the priority mail in the US from hub to hub). But, any time I've heard of people having problems, I've always heard that Metzer's went out of its way to resolve them to the customer's satisfaction.
I would definitely order from them again. If only I could figure out how to POSSIBLY justify getting any more ducks!