Cardio-Kickboxing anyone?

I have been working out with a personal trainer for about 2 months. She is reccommending a cardio-kickboxing class (gloves and all). It is a 1 hr class and seems very intense. I was told I could "work at my own pace". Does anyone have any experience with this type of class. Its at a local juijitsu dojo where my son just started martial arts classes.