When you mix in the fact that the classes and sub classes don't make a huge change at all, you find yourself hitting the wall really quickly. (p4gamers.com)
Throughout the beta you were able to select from the familiar classes of Titan, Warlock, and Hunter with the addition of new sub classes for each being the Sentinel for Titan, Arcstrider for Hunter, and Dawnblade for Warlock. (relevant-gaming.com)
The Taken King sees the debut of the long awaited Sub Classes, each pertaining to a one of three original classes, The Hunter, The Warlock, and The Titan. (nonfictiongaming.com)