I used it once, even posted some pics in a thread.
In short it works amazingly well for oil, grime, dirt etc. You could eat off the engine and front+rear suspension.
Will do some paint and some not. Did not take much of my front and rear suspension.
The rubber under the E9? Nope. The guy tried for hours but it would not come off.
The nice thing is that since it is not abrasive it will not damage hoses, plastic etc.
BUT, it may remove paint so you need to be a little careful around paint you want to keep.