Very good advice in the two posts above. Stay clear of these offers unless you know exactly what you're doing and are aware of all of the potential downsides, such as escalating maintenance costs and limited availability for the times you might want to go on vacation. Also be aware of a hard sell if you visit the property in person, during which the agent will tell you the "great offer" expires at the end of the day or tomorrow, not giving you time to think it through.

I don't know if these factors apply to this specific offer, but a friend of mine took up something similar from Starwood and has intensely regretted it ever since.