If a person can qualify for a $17,000 personal loan at their bank, that's likely a better idea.
For those that can't convince their banks to do that, and don't want to spend the time saving it up, the way Disney does it isn't heinous...they make it BEYOND easy to pay extra (there's a link right there on the website to make extra principal payments in amounts over $10), there are no penalties for paying it off early, it's a monthly bank draft...completely simple.
I would add to ToddyLu's statement something else (I'm paraphrasing someone else's great wording that goes along with my thoughts)...as long as you are very up front with yourself and your checkbook that you will be paying extra in interest, and you're not going to lie to yourself about all of that, then if it's what you need to do, it's not a horrible thing. Just don't lie to yourself about the interest.