yeah it works. I hate it though. The Friday high rep workouts always decimate me. There's something about doing 30 step ups or lunges in a row that has of way of ruining my weekend.
But anyway, if you stick with it and eat enough, you'll see results. If you're like me, and hate the high rep work, Waterbury Method was really nice for me. All my core lifts went up quite a bit in the month I was on it; 10x3 can work wonders if you've never done it before.