I visited Seaside, Florida on business at the time that movie was filmed there. They did not have hardly any props, and the actual town was readily recognizable in the movie. It is a nice town and it has character, don't know about soul. It has existed for a few decades. The vision was purely architectural: small lots, plenty of walking/biking space, community buildings, that kind of thing. This creates an environment where people bump into each other, making for a lively public space, uncommon in America. I haven't been to Celebration, but I would not describe Seaside as creepy. The movie, of course, introduced the creepiness in spades.
Celebration is creepy 8-) from its faux olde water tower at the entrance, to the three shades of off-white houses, to the seemingly endless grid of streets and canals. It's worth seeing.