I've used it quite a bit. Ironically enough, I've seen the lowest prices at Costco (the bulk package) and WHOLE FOODS (the individual bars). I couldn't believe my eyes last year when I went in Whole Foods for my annual I'm-in-the-area-so-why-not stop into the store. Of course, everything else on the shelves seemed to be 30-100% more than the equivalent item at Kroger, but the Kerry Gold was actually cheaper.
A friend of mine used to shop there a lot more, and he said they occasionally put it on sale for 2.50 a bar or so. I've seen it sold for twice that at Kroger.
Moral of the story - if you can get it for a good price, it's worth buying. I prefer the salted butter, but some purists use only the unsalted. If you are doing the butter in your coffee thing, I think the unsalted butter probably froths better.