Without going into spoilers, Resident Evil 2 (both the original and the recent remake) have two "scenarios", A and B, which are radically quite different from each other. It reflects on the fact that the two protagonists (Leon and Claire) get separated at the start of the game due to a car crash and go their separate ways (though their paths often intersect), and depending on which side of the car crash they end up (player's choice of which character they want to play as first) one takes scenario A while the other takes scenario B. This means when the player does Leon Scenario A he then unlocks Claire Scenario B, or if he did Claire Scenario A he then unlocks Leon Scenario B.
The reviewer made a mistake my playing Leon Scenario A and then Claire Scenario A, which means he played the same story progression with both characters, not only skipping half the story but playing the same scenario twice back-to-back with minimal differences. He deducted points from the score of the game (which has so far recieved rave reviews for both being very faithful to the original while modernizing some key aspects), which generated backlash because it was a mistake from the reviewer and not the developers.