The ST-60B thermal cooker is OK but compared to the THERMOS brand cookers the performance doesn't measure up.
The THERMOS brand thermal cookers all use a vacuum insulated outer pot which will keep things hot (above 140 degrees) for about 12 hours.
In my testing of thermal cooker performance I would bring an inner pot full of water to a boil and then place it in the outer pot. The Thermos thermal cookers would keep the water above 140 degrees when I measured it 12 hours later. The ST-60B and other thermal cookers that used a foam insulated outer pot would only keep the water around 80 degrees after 12 hours. I've tested a number of brands and models and the Thermos models with the bail handles are the best made and best performing thermal cookers available. Note that the 140 degree temperature mark is important because it's the level at which bacteria starts to grow. Food kept 140 degrees or above will not be as likely to get you sick.
The inner pots of the ST-60B are made of very thin metal compared to the Thermos cookers so you can scorch food much easier as you bring it up to boiling temperatures. The Thermos inner pots are made of nice heavy stainless steel and have a clad bottom which makes them great to use for any recipe.
I bought my Nissan/Thermos thermal cooker years ago when Thermos still sold them in the US market but it's hard to find them at all unless you shop outside the country.
I'm not a Thermos dealer but I do love my thermal cookers and started the
thermalcooker.wordpress.com blog to collect the info about them. As people have asked me where I got mine I've collected a few sources on where they can be purchased, send me a PM and I'll give you the details.