We have used them in the past and it actually works fairly well and easily.
You will be taken from the airport to the downtown bus station (very nice BTW) and from there you use a free transfer to go to Disney's Ticket and Transportation Center. From there you use Disney transportation to your resort or to a park.
We have used it two years in a row and had no problems what so every with them. The buses were clean and the drivers friendly and helpful.
I think the cost is now $1.50 per person with free transfers.