We did this a week and half ago and it was great. We had a early appointment for my daughter at BBB and we went in with everyone else who had early dining ressies. It was a 8:30 reservation and we got in early so we had plenty of time to take in the sites and stop and use our photopass + as there were photographers everywhere. We got some great pictures and my daughter loved it. Then we got into her reservation early and were done by 8:45 so we went out front of the castle and were the basically the only ones around. We got some more pictures and my daughter had to go back to the one photographer because she "had" to show her the makeover. At one point I looked around and thought, it is my wife, my daughter, me and photographers with main street all to ourselves. We listened to the opening and then just sat back and watched everyone come down main street. Talk about a sight. It is just crazy seeing it from that view. Some were running like the running of the bulls was going on and that bull was right behind them (got to get those fastpasses I guess), others were just strolling along taking in the sights. Everyone had a huge smile though and it was a picture perfect time of happiness. It was a great "people watching" opportunity and a totally different sight that you normally don't see at Disney.
This was a memory that will be engraved for a long time as it doesn't always work out that way with reservations and then to have others have the reservations and no one be around. It was a special time and my little Cinderella was so happy.