I'm doing it right now. I started just from the book "5 Factor Fitness" (now there's a "5 Factor Diet," which I haven't read), but I recently signed up for the online program, which is more customized, especially for women. It's a little pricey, though.
Anyway, I like it because I have practically no discipline when it comes to the gym, but it's hard to justify avoiding a 25 minute workout, even 5 times a week. I think it's probably best for people who either have very easy access to a gym (in your office or apartment building) or who work out at home. I think it would be hard to drive to the gym (and park, and the whole headache) five times a week.
I just started a 5 Factor traineo group at 5factor.groups.traineo.com. Please join!