I have recently discovered thicken cream and what it does if used in one's icing. It makes it amazing that's what! In the wise words of Black Eyed Peas, I think about it every night and day, I am addicted and I just can't get enough (vocals in the background: I just can't get enough). There is always a tub of thicken cream in my fridge for the times when I a have an emergency need to bake.
Using thicken cream instead of milk or water makes the icing richer and in my opinion more tastier. Also, I find that using cream reduces the sweetness of the icing sugar and gives the icing more of a creamy dairy flavour.
For instance, I use thicken cream in my ice coffee icing oppose to milk. It does mean that the icing doesn't set as nicely, i.e. harden, and can be at times a little runny. But the trade off is worth it!
Now that I have found thicken cream, I will never go back. The more cream the better, I say!