I did the new Cookie Jar shake on our trip in January and it was great! It was better than a previous one I tried when they first opened, and better than the the cookie sundae I had before as well. I will say that the shakes themselves are pretty basic - not much mixed in it, so once you get past all the whipped cream and stuff piled on top, its your average shake.
I will also caution that we got the chocolate almond bread as an app (amazing), our entree, and then we each got a shake and my stomach was bursting at the seams. LOL! We normally have pretty good appetites but all that was too much for even us!