I don't know why but the DmC Tweet says there is technically three levels. Two levels AND a Boss Fight.
"Time to face your demons! #DmC demo arrives on XBLA & PSN 20th Nov (21st Nov for EU PSN)! Play 2 levels & 1 boss fight! http://bit.ly/XEzhJI" --- The internet was made specifically for you...LOL...I lied.