Yes, I used them for my trip last January, and I'm using them again for this January. I didn't have any problems, and it was nice to let someone else worry about discount codes and ADR's.
They weren't able to save me any additional money on my last reservation (other than the AAA discount they originally booked me with) because I was not willing to change resorts. If I had been, I could have saved more with the AP discount. They took care of watching for the code and checking availability. I'm hoping I'll have better luck this time around.
They were able to get me all the ADR's I wanted for my trip in January 09, even though I didn't make the reservation until past the 180 day mark. I just gave them a list of what restaurants I wanted, and approximate days and times and let them handle the rest. It probably helped a lot that I was very flexible about dates, but again, it was nice to let someone else do the grunt work.
I don't use them every time. I feel a little awkward using them for my fall trips during hurricane season, when I could have to cancel at the last minute. I don't like the idea of them losing out on commission if I have to cancel. But that's a personal preference, and I wouldn't hesitate to use them again.