Ive never used one but ive seen them in action.
My opinion is that if you already dont have sweet random flow either via something like Tunzes on a controller or a OM unit on a cls, you should defintely invest in one of those options first as they will provide you with a heck of a lot more benefit than a wavemaker
Dont get me wrong...they are cool...but should be added in addition to sweet overall random tank flow, not to be relied upon for it