The flavor was great--subtle maple flavor and pretty sweet. Mine came out more like a thick glaze, which would work great on doughnuts or cinnamon rolls (luckily that's what I wanted it for). I added extra powdered sugar to thicken it a little, but with the amount of syrup I think you'd need quite a bit more sugar to get a fluffy frosting consistency. A maple extract instead of syrup would help with that issue, if you have any.
This frosting came great. I followed the recipe to a T and didn't require any additional maple extract. The maple flavor is subtle yet distinct (I used grade B maple syrup, the darker kind). The consistency is thick and creamy and pipes well. I will absolutely use this again in the future! It's simple and delicious.