I have to say, after trying this on Friday, this is my new main exercise. I did them for about 20 minutes with short breaks, at the sidewalk outside my weight room, with 54 lb kettlebells in each hand. This left my legs sore for 3 days, and my arms got worked too, seeing as I bench pressed after I finished and my arms were shaking twice as much as usual, and my military presses were hampered due to my shoulders and traps already being worked. A less workout-experienced buddy of mine did a similar length workout with 2 sets (actually, 1 set at about 10:00 and another at about 2:40) and 36 lb kettlebells, and his legs are so worked that they shake whenever he tries to use his leg muscles.

As for how far down I go, I make sure my back knee lightly touches the ground, then go back up, take a step forward, and do the same with the other leg, and repeat. I had immense pump in my leg muscles and ass muscles after this, and despite losing that pump after a few hours, the fatigue remained, and the day after that, my legs were sore all over, inner thighs, hammies, quads, glutes, you name it. I'm going to get monster legs this way, and am working toward being able to bust out about 20 minutes worth with two 100lb dumbbells.

And yes, I find these to be significantly more fun than squats.

Great exercise.

You will be a bloody quad monster if you can do that with two 100 pounders!

Just be careful to not let your back knee go down too far. You should keep it more than an inch above the ground when you lunge.

How come? I usually let it very lightly tap the ground (if on cement) or touch the blade of grass when I'm on turf.

If you like that, you should try dragging a weight sled attached to your hips. It's a designated power move.