I've done a few and they've helped but can't say wether it is solely down to them as I tend to combine with other workouts. They do help though. I find it's good to have a fixed schedule plus some others to push me further. It's also good to have something in place that provides variation as otherwise I probably would subconsciously stick to only doing the workouts I like and use often. This way, I get the best of both.
I've done the free ones n I've seen improvement in strength and body definition. Any exercise works long as consistent and cardio is needed.
I finished more programs, I do 2-3 at the same time usually. I have lost weight, I gained a little muscle and my wife tells me my silhouette really started to change.
I haven't finished a programme yet (because I have a 4-day a week gym programme now so I use the Skimble programme as an off-day work out.) But in the 2 weeks before I started gym, I was doing 2 programmes and I could definitely notice a difference in strength! Big time. And I even lost 2kgs. It's important to eat correctly too if you really want to see a change.
I'm the same as Hadi, I've completed a few but I do them along with my regular workouts so I can't say exactly if they work. The ab foundation and V taper programs are pretty good, they gave me workouts that I'd never tried before and were a nice way to mix things up. I like the yoga ones too because I tend to forget to keep up with yoga in pursuit of my results! Bottom line: they are great at keeping you on schedule and focused but the person who makes them work is you! You are in charge of your own results!