i didn't say i had a good experience with knewton
, just that i think it's excellent for people who like learning from video lectures (i presonally don't). i just did the free trial back when it was offered, and opted out. i didn't buy mastergmat either, even though i liked it much more.
re the money back guarantee, i think you are misleading people by writing on your site
"How does the guarantee work?
Simple. If you do the work and don’t gain at least 50 points on your score, we’ll refund 100% of your course fee. We’ll ask for a copy of your official score report, which we’ll compare to your previous score (if you have one) or your first Knewton
it's not so simple... you also require the person to jump through a series of hoops that for many ppl would be unrealistic given their time constraints etc.
i wish i had a better suggestion for you on what criteria to apply for eligibility for the refund. i completely understand your concern on people not putting in the effort not deserving a refund... in any case, i think that as an honest business you shouldn't hide such a huge caveat in the fine print buried somewhere