That's good for a 1-hour steak, but I wouldn't do eggs this way (needs more precise temp) or a 72-hour short rib braise (needs stable heat for longer).

I agree--and even for one hour timeframes, be sure to check your ending temperature to make sure it didn't cool off too much. I'm not a fan of the beer-cooler method for this reason (although with care, of course, it's safe).