This is my first experience at a HIIT workout class. I have had my share of personal training sessions at other gyms but this was totally different. They have several classes starting from 5:30 in the morning. I am a morning person and so I have just attended the morning classes. The sessions typically include cardio (treadmills and rowers), core workouts and weights. Each class is different and so you will not feel bored at all.
My wife and I generally took two classes a week. The trainers are really good. We have trained with Jill, Holly and Jaimie. They are all equally good. There are others who train in the eve classes. I bet they are good too!
The 6:15 classes are mostly full and so we go during the 6:45 classes. They have tv monitors on the floor that listen to heart rate pods (wrist and chest). So you get an idea on the level of intensity that you are going through and accordingly can pace yourself.
There is a social aspect to it since it is a group exercise and we tend to push ourselves as we don't want to look sloppy in front of others. There is no push and you can pace it at your own comfort level. I initially thought it might be a little intimidating but it was not. If you are uncomfortable with certain exercises, you can let the trainer know and they will give you alternatives. It's all cool at OTF!