since starting CC, what has your results been? (weight loss, increased cardiovascular endurance, defined muscle definition in legs etc.) how many times a week are you doing these workouts and how do they differ from itread?
I've been doing CC workouts for almost 3 years now. I have a great deal of difficulty with workouts like step, hi/lo, and kickboxing, and I prefer machine cardio so CC is a perfect fit for me! I do them about 3 times a week -- sometimes more. Even though they are interval workouts, I have been known to do them as steady state from time to time because I need to do cardio more than 3 times a week, and I NEED the kind of motivation that only Sean O'Malley can provide.
I've had GREAT results with CC, especially in terms of my cardiovascular endurance. When I did my first CC workout I could barely make it through Volume 1. I do the workouts on an elliptical and in the beginning my performance was so poor it was embarrassing

. I had to keep the resistance low (level 3 on a Precor was the highest setting I could use), and my stride counts were pathetic. Fast forward 2 1/2 years and I now warm-up at the same pace I once used for sprints

. And I can really crank the resistance on those hill climbs!! I have slimmed down through my thighs, glutes, and hips. My legs and glutes are very firm and STRONG!! I also use weights and kettlebells which contributed to my results, but still, when you use a lot of resistance on an elliptical it's bound to help shape your lower body.
In terms of weight loss, I can't say I've had great results, but that's because I don't have my diet under control. I eat a nutritious diet, I just eat too much... and the daily desserts don't help matters any. Cooking as a hobby proved to be a drawback as well.
I can't recommend CC workouts strongly enough! It's my cardio of choice and what I've used solely with STS -- they compliment each other beautifully. I love that you can use CC with any equipment, and recently I've started running outside with it!!!! I also like that he uses perceived exertion so I can work at my own pace (this is thoroughly explained on his website in the Quick Start Guide
http://www.cardiocoach.com/Quickstart.php ). His sale is over but please don't let that stop you from purchasing the workouts. They are SO wonderful and worth every penny!
ETA that as your fitness level improves the CC workouts will grow with you! I kid you not, Volume 1 still kicks my butt because the strength and endurance I've gained allows me to take it up to a higher level. What was my level 3 two years ago is now my level 1 or 2.