All it really is is a plan to pre-pay for things. Nothing really else.
Depending on the number of days, you do get some vouchers for a character meal (breakfast, I think?) or two or even more, and depending on what you choose you can get a few dollars of value from that.
But other than that it's vouchers in certain denominations.
Which sounds nice, but they don't give change! So if you buy something for 4.50 and you pay with a $5 voucher, you lose that 50 cents. So then you buy something else, bringing the total up above the voucher, and you have to pay cash for the extra.
When I think about future plans for WDW, I can see figuring out how to get good value from the dining plan's credits (difficult to begin with b/c we're not big eaters and we're vegetarian, so it's questionable as to whether the dining plan at WDW makes sense in the first place, but I'm *trying* to make it so, LOL), but the idea of figuring out how to not lose money or spend extra money for the DLR dining plan just doesn't interest me.
There are those here who enjoy it, though, and get it often!
For me, I prefer to save the amount I think I'll need (menus are hidden away on allears.net and dlresortinfo (but not on wdwinfo.com for some reason!) so you can think about what you might want) and get giftcards ahead of time, or buy them at the beginning of my stay. Actually I usually split it into days, and get a new giftcard or refill an old one each day, but that's just my preference. That way I've pre-paid it, but I'm not losing anything, b/c the giftcards don't expire and can be used in all sorts of places.
Have fun planning! Check out HydroGuy's tips in the sticky towards the top of the forum.
