Yes, it is fermentable. It will boost your ABV a bit over fruit without syrup. As an experiment, I made a batch of blueberry and a batch of key lime wine with Golden Eagle Syrup, a blend of corn syrup, cane syrup, and honey which is available here in the South. I was interested in seeing if they would resemble a mead or melomel. The end results had no resemblance to mead, but they both came out as some rather nice wines. I gave most of the blueberry away for Christmas and everyone who got a bottle complimented it highly.
If it were me I don't think I'd pay extra for fruit without corn syrup, but don't count on it to add anything to the flavor. Depending on the recipe you may or may not want to try to account for it in your added sugar.
Hickory Glynn Winery & Brewery