Not an easy question. Timeshares are a big responsibility, even when given to you for free. That maintenance fee is due every year, whether you use it or not. Before you say yes or no, spend some time getting educated. Visit
www.tug2.net and
www.tugbbs.com (The Timeshare User Group); it's like the DISBoard for Timeshare owners and you will get tons of advice (most of it good, all of it will make you think). Are you going to want to visit Orlando regularly, always on week 18 (late April/early May)? If you plan to trade through RCI or II, what is the week worth in trading power? If it is a lockoff 3BR, it may be worth a ton, but I'm not sure what the trading power is for week 18, or even if the HIVC deposits your actual week. Are you even allowed to participate in HIVC on a resale, generally for most "clubs" or "plans" the club membership is not transferrable to a resale owner so you are left with just the underlying week. I'm not sure on the transfer question, but you NEED to be.
I own two Orlando timeshares, and I have no real regrets, I bought both resale for about $12 total, and I love the lifestyle and the resorts and Orlando. BUT if I were to do it all again I would just rent. Same price as my MF's or cheaper and no annual obligation.
As for Orange Lake, it is a nice resort, huge, with lots of amenities. I have never stayed but have a co-worker who owns there (for many many years; his 30something siblings all took the membership over from their parents) and they are happy with their ownership. In reading comments on the resort over time, I think it may be slipping a bit since the Holiday Inn shingle went out front a few years ago (comments seem to be getting more negative).
My best suggestion as it sounds like you haven't been there yet, rent it from them this year for their MF cost. If you really like it, and you have taken some time to understand what you are buying, take it off his/her hands.