Just watch for snow in the main distribution hubs. Sometimes overnights get held up that way. Other than that it's pretty safe. I still have some fish that got held up and lived through the second day. Actually that shipment had about 7 fish and was about $400+ and all lived.
They do use 40 hr heat packs like they should. The only thing that bothers me is they just toss the heat packs in wherever they fall. They used to tape them to the top of the box which is better IMO and they should go back to that method. But I never had a problem from it. Not to mention 14 day no questions asked guarantee.