A common opinion of people in this form is that it's reather useless. If you want to learn to pick properly, you should purchase a real pickset.
Further, you should not start lockpicking by learning to rake. If you want to really to be able to pick it with skill and not by luck, you should learn to pick pin by pin. This does not mean that you should never rake. Just that you should learn to pick also. But after all this is a matter of opinion.
And if you want to rake, then purchase a real rake (and a tension wrench if you don't have one). It's a lot cheaper also.
This subject has been discussed before:
viewtopic.php?t=4806&highlight=kwick
viewtopic.php?t=2458&highlight=kwick
