It's easy to track my progress. Base, Push and All-Outs are steadily faster on the treads; I'm using heavier free-weights and quality of form + #reps are improving. There's also no pressure if I'm having a bad day because I'm able to go at my own pace.
I love everything about the work out. The thing that needs work is the selection of music that is played. Some of it feels like I'm in a drawn out club remix for the entire class. I would encourage more variety, especially rock, and more songs that were released before 2012.