I have a gill pulverizer and have found it to be less useful than I had hoped. Granted my teeth are a little rounded, but I have gone over a section of my propery (mostly weeds) in the early spring before the weeds start and it really doesn't do much. It has worked great on loose soil but not so well on compacted soil. I paid $200 at auction for it, so I haven't really lost a lot of money, and I have actually found it to be pretty usefull for breaking up and smoothing my gravel driveway.
My cousin also used it to level and smooth a bunch of his land, mostly where a new septic system was installed. He was satisfied with the results.
I think for them to be effective, the soil needs to be loose. I used a 2-bottom plow on my garden in the fall and used the pulverizer to smooth it out in the spring and it worked great. I have about an acre and a half that I want to smooth and when the time comes I will probably plow it first and let it sit for a couple months then go over it with the pulverizer.