I've been using the Gold Gym's resistance tubes for about two months now.
The results are very satisfying for me. I just put in the DVD video that came with the equipment and do the routine. It takes about a half hour to complete. I always work up a sweat but the routine is just enough, not too much or too little. You increase the resistance by adding extra tubes. Normally I use the black (intermediate) tube but I will add the red tube for certain exercises and I use all three tubes for the abdomen exercises and leg stretches.
I have been doing this every other day but I am now pushing it up to 4-5 times a week.
Long Series Resistance Tube Kit, Included DVD Workout ~Gold's Gym
Long Resistance Tube ~Athletic Works