You can see your workout results on the Fitness app on your iPhone. It's helpful to see all the data on one screen. I also like the heart-rate graph at the bottom, so you can see what parts of the workout were the most and least active.
Compared to a 30-minute brisk walk that includes hills, which for me burns about 182 active calories, and a 30-minute run, which burns about 217 calories, 128 active calories seems pretty low. My heart rate definitely gets higher walking or running, as high as 172 BPM, compared to 152 during this dance workout, so I assume that's why the calorie count is higher when I do those activities.