Since there are no enforced rules, The Chessboard is great for remote chess discussions and lessons. Pieces can be moved freely; you can even move the opponent's pieces. An online shared chessboard.
Design is minimal and functional. You get the maximum board size possible on an iPad screen. Without useless frames and decoration.
In summary, no "it's black turn" labels, no rule enforcement, no computer opponent: you get nothing but a chessboard. And of course no ads.