It was fantastic. Convenient pick up at our hotel and drop off. The sites were amazing. Our guide was knowledgeable and engaging. We were the only full day guests, so we ended up with a private tour in the afternoon. I would recommend the full day in order to see everything.
This is a must see! Take the tour even if it is to avoid the lines at the entrance. The palace is incredible, and the gardens are beyond description. Go on the days that the fountain show is on, it is worth it. Our guide used wireless headsets to talk to us, and this let us wander around in the rooms and still listen to his commentary. Buy the book at Versailles; it will provide you with pictures in rooms you can't take photos, plus they are also better than you would be able to take yourself.