We just got back. The things I enjoyed with concierge are:
1) Being able to walk to the lounge and get a snack or drink. This is especially useful with a 3 year old who one minute says "I so full" at a meal and then 30 minutes later "I so hungry and thirsty!". We also would take one or two cereal boxes with us to the parks for a quick snack fix for our son.
2) Having robes in the room and turndown service.
3) Getting a welcome phone call message from concierge as well as nightly phone messages from concierge with the weather report for the next day as well as all the park hours and which park is early entry.
4) Being able to walk to the concierge desk and cancel or book a priority seating, usually without a wait.
5) Our experience with WL Concierge was excellent - they went out of their way to be helpful and there was always someone readily available to ask any questions.
You will love your stay!