Obviously, you'll hear a wide range of opinions about this.
My wife and I have done concierge a couple times -- once, at the
Disneyland Hotel, because we got a good deal, and another time at the Board Walk, because it was the only room available.
It was interesting to try, but I don' t know that I'd do it again.
The breakfast in the morning was decent -- cereal, yogurt, breakfast rolls, fruit, juice and coffee. But the rest of the day the food was fairly mediocre. And, after a couple days, dull. (Though I confess some of the cordials late at night were nifty -- but who has room for that after a big Disney World dinner?)
The other perks -- someone to check reservations and make phone calls and do the detail work for you -- really didn't make it all that worthwhile for us. Perhaps, if you're traveling with kids, it makes a difference. For just the two of us, it didn't. (One big and perhaps significant exception: concierge was able to nail us a ps at Cinderella's Royal Table for breakfast -- the kind of hot ticket some parents would KILL for
!)
All considered, was it worth the extra bucks? I don't think so. But like so many things, it's really a matter of taste.