Time Sharing Travel Memberships, are they really worth it?

No, it's not worth it. You actually don't pre-pay for a week's stay, you buy a share of the property and get a weeks stay assigned. In essence it's a real estate transaction. With that property purchase come all kinds of obligations even though it's just a share. You have to pay maintenance and eventually renovation fees, you have to pay tax, and much more. You can't just pick a week, the week is assigned to you with the purchase. You can switch with another 'owner' but that doesn't always work out. Most people end up sending friends and relatives on a vacation if they themselves can't go. Also, it's not easy to sell the property share. It usually sells for much less than what you bought it for. And there are fees associated with that as well, too.