My "500" Corona style mill works very well. You just have to accept the fact that they are cheaply manufactured and need to be adjusted to provide a quality crush. If you have a reasonable amount of mechanical apptitude, these things can work real well, and once set they seem to stay that way. I run mine w/ a big a-- drill and hopper...link in sig.
If you are the type that expects your mill to run well "out of the box", you're better off getting a more expensive roller mill, aka Barley Crusher.