Firstly, I must point out (as I often do when discussing such things) that "fear" itself is subjective- what one person may find to be simply terrifying may only be a simple chill to another. Either way, there is a definate possibility that at least one part of the game will contain some sort of disturbing atmosphere. In the past, though the Zelda series in general contains a vast number of relatively "disturbing" creatures, Nintendo has gone out of its way to include a dungeon that is themed around a creepy atmosphere (whether it be the dead warriors of Arbiter's Grounds in TP or the decaying thresholds of the Skull Dungeon in aLttP). I suppose it would be most uncharacteristic of them if they deemed some form of disturbing area in Skyward Sword unnecessary. There will likely be a return of Redeads, Wallmasters, and other series staples. I suppose there may also exist parts where enemies appear unexpectedly or you feel that Link is not quite alone. Will it compare to any standard of great horror? This is unlikely. Will there be parts that give rise to some emotions of dread? I certainly hope so.