The intensity is great, the trainers have been awesome and really push you to your limits. The dynamic encorporated in each class works wonders for targeting specific muscles and the diversity of them is fantastic! I've had great results from OTF and is my go to for HIIT training
I like the fact that I don't have to think about what I'm doing in my workout, I just follow instructions. I also like that as I get fitter it's easy to push myself to do things I don't normally do in order to keep my heart rate up to get splat points. It's kind of addictive.