Technically if you give some money now upfront you will get that specific club room for a longer period of time than you would by paying cash every year. Biggest downside for me is reduced number of such properties. For people up-to-date with promos, offers, hotel point schemes, this is highly unprofitable, as you maximize your benefits in other ways.
I attended a similar presentation from Mariott few months ago and I could only agree that the offer is not for me, but a reasonably good one if you fit in the target audience.