Kariev,
I'm new to barre workouts, but I can see that the principle is similar in some ways to Pilates: controlled movement and "deep strengthening". (Please someone correct me if I'm talking nonsense!)
I have seen nice changes in my body when I have combined circuits (TM, Firm, even Jillian Michael's 30DS) with Pilates, cardio, and sensible eating (no overeating, reducing sugar..... you know!!!!)
I have seen my legs thin and more definition in my abs from adding the controlled form of exercise. Let's see what barre does for me!
I like doing both and I find dropping circuits a bit "scary"