This festival was amazing. I went to the 2014 festival, and it was in the shops at City Center. We had a VIP pass so we got to go earlier than most. It was definitely worth the money because once everyone gets there, there are large lines.
The chocolates were amazing! They also served beer and wine in addition. It was not an all night event, maybe a couple hours worth, but it was so worth it. The chocolates and desserts were so intricately made, and the gift boxes that you get from the booth from the Bellagio's Jean Philippe Chocolates and Patisserie would actually cost you around the same price as the ticket to the festival. You also receive your own wine glass and carrying tote to take home samples in.
I have seen some bad reviews on here of this festival, but I encourage you to try it anyways, it seems to be getting better and better every year, as most festivals and shows tend to do.
I will definitely be going to the 2015 Chocolate Festival and Pastry Show.