I think this is an excellent way of working out, once are a pretty advanced lifter with a good base of muscle and good technique, and can lift heavy.
I wouldn't go directly from doing a total body workout 2 or 3 times a week to doing a "each body part once a week" routine. Instead, make your way first through a two-day split (upper and lower body worked separately, two days a week each), then go on to a three-day split (working each body part once a week, but several body parts each day), then finally onto a "one body part per day" routine (you could even do a 4-day split in between here, but none of Cathe's workouts are split that way out of the box). Working the entire body two, then three, days a week is what is often recommended for beginning weight trainers. After you've done that for a while, if you want to make progress, it's time to go on to the 2-, then 3-, (then 4-) then 5-day split. Then you can mix things up and do different types of workouts on different rotations.
P90X is a "each body part once a week" type of workout (a three-day split, though, rather than a "one body part per day" split), and it was very effective for me. The combination of working out as hard as you can, followed by allowing each muscle group recovery time, really helps with strength and muscle-size gain (at least in the upper body, for me, and more strength than size, which I like).