I've done it about 3-4 times when I want to mix it up. It does work well for lean mass and it is harder than it seems at first. The most difficult part is sticking with it because it goes against what you may be used to and you will want to go back to your normal routine.
I've put on 4-5 lbs of muscle in each 6-8 week stint that I did it. Plus it also help get over a plateau I had with deads. I just did this about 4 months ago and I was able to finally get a couple of 455 pulls, which I had never been able to get to.