I used LL with no weights when I was recovering from knee problems early last year. I still felt it in my legs. It's that mean.
These days I use LL with light weights. The most I use are a pair of 15-lb. db's especially since I do those endless squats the way my PT friend taught me -- against the wall with a stability ball between my back and the wall, my feet shoulder width apart (much narrower stance than Cathe's) and pointing about 30 degrees out, the db's at my side. Keeping my weights at 50%-60% of my max and doing more reps has shaped my legs better than using heavy weights, which bulk them up too much. It has also been good for my spine and knees.
I guess this all depends on how your body responds to the workout. I have to go real heavy for upper body to get shape and bulk there, but I can get by with endurance-style work for lower body.
Pinky