I took a class at my gym a couple years ago. Loved it! I think the poles help you get your heart rate up just a bit more.
You do want to make sure you size the poles correctly. When holding the poles vertically, your arms (fingers to elbows) should be at slightly more than 90 degrees. And then, when walking, keep your arms long and let them flow naturally.
Here in MN, we have the Nordic Walking Queen, who taught the class. Here's how she describes Nordic Walking: lindalemke.com/about-nordic-walking/