I can tell you there is no shortage of folks trying it out. I don't know if this is still from the relative "newness" of the product (there always seem to be a "flavor of the month" in the detailing community) or due to the fact that the product works so well.
Personally, I think the color changing aspects of some of these products is a bit "gimmicky" but that's not to say it isn't an effective cleaner. ....or that the color shift isn't useful (i.e. marketing to customers as a detailer, etc.). I have heard others compare it's cleaning ability to P21s Wheel Gel (which I have used myself) but these products do have limitations depending on the application. Unlike some other more potent solutions (i.e. Meguiars Wheel Brightener, etc.), these are considered "safe" for most wheels/surfaces.
IMO/IME, unless the wheels are really caked, these products work fine. ....and agitation can really help as well. However, if you use a wax/sealant to help protect your wheels (and make them easier to clean), just realize that these cleaners will likely compromise them.
I bought it to clean the wheels on my wifes BMW. I don't know what the Germans use in their brake pads, but they sure do create a lot of dust and boy does it stick to the wheels. I found this to be one of the few cleaners that actually worked without much additional effort on my part. I also found that after repeated cleanings, the wheels got better over time, by the product removing some baked on dust that would not come off no matter what I did to it. So in my opinion, it is a good product.