It is a quick digesting carb. On it's own it will spike your insulin. If you don't want that have it with a protein or fat source which slows down the digestion process of the potato while also lowering the overall GI of the meal.
so would they be good right before a workout for energy?
Slow digesting is much better because it will provide you will slow sustained release of carbs over several hours. Where as the potatoes high GI will have you PUMPED for 10 minutes and leave you pretty drained once it has digested.