The first world shown in the demo was a lush area, where NiGHTS is pictured soaring over sparkling waterfalls, flying alongside schools of tropical fish, diving between huge bubbles, and darting through narrow tunnels of rock. The gameplay footage was kept brief, but it showed NiGHTS traveling a set path, going through rings, and generally just flying about as in the original NiGHTS game.
The darker side of the game takes place in the Nightmare realm, where you'll encounter the game's bosses. Little was revealed about this world, but Gamespot's Greg Mueller did get a glimpse and a brief description of one of the boss stages. The idea is to have boss stages that play out differently than the usual combat-focused boss stages. The example given was a huge, patchwork jester-looking boss that behaves like a giant rubber ball. It's your job to bounce the boss through a maze and get him to the top of a tower. Very little information was given beyond that, and they didn't get to see much of the battle in motion, but if nothing else it seems like the bosses in Journey of Dreams could be an interesting change of pace from the typical boss encounters in other games.
More details available.