If you've been working out with Cathe and Tony, "Slim in Six" would probably not be advanced enough for you (though the third workout of the bunch is more advanced than the others). It's a beginner/intermediate program (even moreso now, since they reedited one of the workouts a while ago and it's shorter than it used to be).
The follow-up program, "Slim Series," is an intermediate/advanced program. It focuses on the lower body. There are 6 workouts: one lower body only, 4 that are total body, and one stretch and stabilization. It's set up as kind of a "Freestyle" program, working the lower body most days of the week with high reps and light weights. This works well for the lower body, but not so much for the upper body, IMO, because it can lead to overuse and joint problems if the rotation is followed as they suggest (even the instructor, Debbie Siebers, recommends doing the workouts every other day, not every day).
The pros:
1) the workouts are very space efficient
2) minimal equipment (the lower body workout uses no weights, aside from optional ankle weights, the others use 2 sets of dumbells and/or a resistance band).
3) easy choreography (simple moves that are no-brainers)
4) a "no music" option (great to have, because the music is not that great, and can really be annoying after a while...the simple choreo allows you to follow the beat of your own music--anything from 130-140 bpms seems to work, with 133-135 being ideal.)
5) effective for slimming the lower body'
6) for me, they are great as an 'I don't feel like working out' workout
The cons:
1) the workouts are very, very similar. And the warm-ups are all pretty much the same. I can't even keep them straight in my mind. They can become very tedious, especially if you do them in a rotation (they are best, IMO, in small doses)
2) some people find them mind-numbingly boring (if you like complex cardio, these are NOT for you!)
3) form is sometimes iffy: some backgrounders do deadlifts with really bad form (and Debbie "corrects" one of them, but she still rounds her back and bounces at the bottom of the move); some double-time moves seem unnecessary and are harder on the joints (I found I could deal with this series much better after omitting most of the double time moves) Debbie often has no idea how to do or cue a good kick;
4) May not bother some people, but it can annoy me: Debbie has a rather suspect understanding of anatomy, often saying that X move will work the inner thigh, or that if you turn your leg too much, it will work the inner thigh, seemingly forgetting that we have quads! There are also several supposed "chest" or "back" moves done while standing that are really more of a shoulder move (but if that would annoy you, you can modify them like I do, to make them actual chest or back moves).
Target sells a two-pack of the Slim Series workouts (they might be labelled "Slim in Six," but they are actually from the Slim Series. I'm not sure which two they are, but the titles of the entire series are "Firm it Up"--the lower-body only workout, "Shape it up," "Mix it up," "Tear it up," "Tone it up" and "Cool it off"--the stretch workout.) That would be a way of testing out the program before getting them all.
HTH
