It may "feel even bigger" though. It will have 'non-critical' areas to explore and reward players along with "small events to encourage" mini objectives.
"For simplicity of explanation, as compared to Demon's Souls, the map will be approximately 1.5 times the size. It may feel even bigger to the players," said director Hidetaka Miyazaki. Dark Souls is the spiritual successor to Demon's Souls.
"Not so much hidden maps, but there will be areas that are hidden away that are not critical to game completion. In regards to side quests, they won’t be stated as specific quests, but we will implement small events to encourage players to create their own mini objectives."
The world of Dark Souls must be self-discovered: "I wanted to create a game where, ideally, the player's game play would, "become a story in itself." Hence, there is little difference in terms of approach to the concept of a story from Demon’s Souls."
Dark Souls releases on Xbox 360 and PS3 in the future.