Quite a few Aussie baristas use it in competition, there is always a few cartons in the competitors fridge at all the comps, sometimes they are covered up as the other milk mob sponsor most of the events but dont make a milk with that high a fat content.
To me it tastes like cream (nearly butter!). I do so little milk in coffee that anything higher than "full cream" can really over power the coffee. I guess if you are using a bold coffee, maybe a tad over dark, and maybe with a fair dose of robusta in it then the extra fat would help tame it.
Still, each to their own and if you like the taste and your arteries can handle it then use it!