I use one as a HLT (with some cut up broccoli boxes taped on the side and bottom as insulation) and also used one as a red wine primary fermentation vessel. For the price, as long as you are not doing anything silly with it, they are very handy vessels. If only they made a 30 or 40L one with slightly thicker walls.
I use it for all sort of things, especially as a double boiler for cheesemaking, sterilising,etc.
Put a dollar store thing (those things made of thin tin that disperses the heat a little) under it to reduce caramelsation.