I love these for the cardio; I have the Deluxe workouts as well as the basic package.
I bought them to use along with other workouts, not as a standalone program... I'll use up to two Insanities in a week, in between strength training and other styles of cardio. That works very well. My body doesn't like to be blasted with high intensity cardio every day
I don't envision using Insanity as a stand-alone program, and I don't use the dvds every week so as not to get bored - but I certainly love them and they were worth the (expensive) pricetag.