FEZ is a unique puzzle platformer that uses a 3D to 2D projection mechanic for navigating through levels.
Con Loads of backtracking
The world is an intertwined maze that rely on specific portals to travel between. Since the entire game revolves around locating cubes -- a minimum of 32 cubes are required to reach the game's ending (64 cubes and "anti-cubes" exist in total). A considerable amount of backtracking is needed to locate the needed cubes; which are intentionally difficult to find and acquire.
Con Guess-and-check instead of intuitive puzzles
Unlike other great puzzle games like Portal or Braid, many of the levels in Fez are unpredictable. You can't just look at the map and predict exactly what to do. You have to guess and check, and not all of the results are intuitive. While guess-and-check puzzles works well for games like The Witness, it's really tedious in a game like Fez.