Made this to put on 24 Rainbow Cupcakes and had plenty left over. I used clear vanilla and butter flavored shortening. The icing came out off-white, so if you want pure white icing, use white shortening.
The flavor was really good and the butter flavor was a welcome addition. I didn't think it was too sweet - granted each person will have a different perspective on what constitutes "too sweet". If it helps, I'm more of a carb-addict than a sugar-addict, so I would say my taste buds are more sugar sensitive than those of you who crave sweets.
I needed to add more water because it was just too difficult to ice the cupcakes w/o destroying them with just the 4 T of water as the recipe called for. Easy enough though.
All in all, I'd definitely use this again.