The 500 degree oven caused my whole house to become filled with smoke and the smoke alarms went off! When the 2 hours was up the roast was way too rare to eat (and I like my prime rib rare). I calculated the time just the way the instructions said. We had to put the $80.00 roast back in the oven on 400 for an extra 30 minutes, the rest of the meal was ready so it all had to be put on hold, including the Yorkshire Pudding!! All in all I was very disappointed. I also had trouble getting the butter mixture to stick to the roast. We ended up using a kitchen torch to soften the butter on the roast so it would spread, and then the spices slid partway off the meat and made one thick pile of "bark" on the top edge of the roast. It tasted great, but did not look very appetizing.