I think it depends if you have kids, stroller or will be going back and forth from the park.
If you have a stroller I would strongly suggest not using ART. It is a PITA!!! You can also plan for your trip each way to take anywhere from 30-60 minutes, depending on the amount of stops and how long you have to wait for it. Also at the end of the day the shuttles are VERY crowded. You may have to wait for a whole round trip before you are able to get on. The last thing you want to do when you are ready to be back at your hotel is sit and wait for the art, especially if you have tired little ones.