Performance wise.. its about the same as a five day ice chest even though I have 2 inches of insulation on the sides and top and 3 inches on the bottom. It doesnt keep things cool as long as I thought it would.. but its also not at all bad. Exact temps. Im not sure. Its not as cool as a fridge but Ive kept milk fresh in it for something like nearly 10 days last summer. I had an experiment going on with it where I have two chambers. One chamber was going to hold ice and the other chamber food. The two compartments are vented at the top and bottom to allow natural air circulation that sets up because of a temperature difference. I also have a 1 Watt fan that can aid the natural circulation.
Well.. I never use the fan and the concept of a chamber for ice and a chamber for food sort of works.. but if I were going to do it again I would just have one big chamber. I have two lids which I do like. Im actually filling the ice chest up today to head to Chula Vista CA tomorrow and am freezing two gallon jugs of water that will go in the smaller ice side (forward). Steaks and some other prepared food are going in the bags I posted earlier.. plus a few six packs of beer and other misc stuff.
The ice chest is something like 83 quarts which I like a LOT especially since a fair amount of the area in the chest is taken up by ice. I have had up to four one gallon frozen water jugs in it and of course you can drink the ice cold water in the jugs.
One thing I did that I really like is having a drain at either end of the chest. I dont get any ice melt with the frozen water jugs but I also sometimes put bags of ice in there. Each morning I drain all the water out of the ice chest. You lose about 10% of the cooling capacity of ice by doing this (draining the water each morning - most of the cooling capacity of ice is in going from just under 0C to just over 0C) but it also tends to keep the ice chest cleaner. Anything that spilled (happens if you sail the boat) somewhat gets cleaned out daily. If I did another, I would spend more time making sure the ice chest had a good low spot where a drain would go.
I think a good seal on the lids in important.. Also by going custom you can really optimize some area for the chest. Overall.. I give it a huge thumbs up..worth doing.