Be very careful about buying one. The maintanence fees will eat you alive if you choose the wrong one. For example, you could pay 3 times the amount in maintenance fees for some properties, than others. For example, you can get low maintenance fees at a Wyndham property in Kauai, and this property is always a "high week" property. You may only go there once in your lifetime, but you trade your week for a week wherever you want to go, as Thea mentions, and meanwhile, you have the lower maintenance fees.
The good things about timeshare ownership:
Huge variety of places to go - some you would never have thought of
Large unit compared to a hotel room
Washer/dryer and kitchen
Ability to eat breakfast in the unit (or any other meal) rather than having to eat out (food flexibility)
The bad things:
Lots of times through a travel agent, you can get a deal for airfare and hotel that is very affordable. If you have to fly to get to the timeshare you've chosen, the airfare is more expensive.
In order to use your timeshare, you have to plan ahead and reserve early, which means you have to KNOW when your vacation time will be. For retirees, that's easier - harder for folks whose work sometimes precludes you from taking off "whenever".
Maintenance fees can run you a lot of money.
Some timeshare companies have in fine print that when you die, the ownership reverts back to them and not to your heirs. (Make sure you know...)
Timeshares are hell to sell, and you won't get any money out of them. Expect it to be for the long haul.
This all being said, we own timeshare and have loved it, BUT, we can afford it. I just went to Hawaii on mine, first time there. But timeshare is not for everyone.
If you decide to do it, buy from Wyndham because it's a large company with the corporate assets to take care of their properties.
Good luck!
Dawn