I've used them with some success and more often I have taken them as a starting point and tweaked them a bit to fit my system or impressions of a certain beer. For the most part I think they are fairly accurate and will get you in the ball park.
Irish Hills Brewery
Primary #1 - Apfelwine #1
Primary #2 -
On Tap - Abbey Road ESB
Next up - Belgian Dark Strong, Apfelwine