If you're new to kickboxing, you might want to try a less advanced workout, like Kathy Smith. The more proficient you become at kickboxing, the faster you can punch and kick safely. KPC is about the same pace as other advanced kickboxing workouts.
I love KPC, and aside from some gratuitous high impact moves (kickboxing doesn't need impact to be intense), think it's a great advanced kickboxing workout.