We have been owners for 10 years, and to be honest, are thinking about getting rid of it. (For a time line, we were Worldmark owners before it merged with Windham, and timeshare credits were much less expensive back then).
It has nothing to do with the resorts themselves, their locations, or yearly member maintainence fees. The resorts are nice and we like them. There are two locations near
Disneyland (one within walking distance), however, we've only managed to stay at one of them (because they are always booked up). The staff and maintainence at the various timeshare units are a mixed bag.
The problem is that for us, everything we want is constantly booked up, except for really remote locations in off season (and alot of these remote locations the local attractions shut down completely during their off season). The first couple years of our timeshare ownership this was not true, and I simply attribute this to the fact that Worldmark has gotten more popular and added more members. So you have to book everything a year in advance and hope you get what you want, which can be a problem with our work schedules. I've yet to actually use the "bonus time" the members can access because none of the locations I want have extra rooms to offer.
Half of our vacations we plan we end up having to pay out of pocket for rooms somewhere else because our timeshare has nothing available. So much for having "vacations paid in advance"!
Also, every location has timeshare sales people hanging around, and many of them are really aggressive which I don't like. Alot of the locations have a "parking fee" which they charge current owners during their stays and will offer to waive if you attend a time share presentation which they say will only last 45 minutes. I've attended two and at the one hour mark have walked out on both and now I just pay whatever stupid parking fee they charge rather than waste anymore vacation time. Some of the more unscrupulous salespeople hang out in the timeshare lobbies 24/7...I've been accosted by them returning to my room really late at 3a.m. My husband and I now make it a game on our stays to find alternate routes through the building to avoid them.
If you buy into them just be aware what you are getting into.