Perfect timing, considering the fact that I was about to post a question regarding OTF and whether anyone had seen results. I looked at their site and videos people posted. From what I understand, a certified trainer watches the class, you all wear heart monitors, and if your rate goes up to a dangerous level, the trainer stops you, but there is a certain zone you reach where you lose weight and work your heart to an ideal level, the orange zone, and that's where the name comes from.
There is interval, crossfit-like training where you spend a few minutes doing weights, then switch to cardiovascular exercise and other things, so your body is constantly stimulated in different ways and you don't reach a plateau. If you're not holding the weights properly, the trainer corrects you. It's somewhat like having a personal trainer, but shared with the rest of the class. You still get the motivation part, just not a fully dedicated hour with a trainer, and won't get hurt or used to doing exercises in an improper manner.
You're supposed to sign up to classes ahead of time. You can't just show up. There are different plans ranging from unlimited classes to a certain amount of classes a month. I'm considering trying it out, I think they have a free introductory class. I Googled before and after photos and the results are pretty surprising. I just wanted to hear personal experiences from fellow moms here. Maybe someone will read your question and post a personal experience.