Since S3, MF has become one of the better AD carries in the game due to her ultimate being able to rapidly apply Black Cleaver charges. She's incredibly strong early-game, like always, but now with black cleaver, her ultimate has insane amounts of utility if your team has someone like Zed or Kha'zix taking advantage of the %armor shred.

Taking advantage of her early-game and snowballing it in a correct manner is imperative. I recommend MF as a beginner AD since her laning phase is so extremely strong, however she lacks an escape and can get picked off easily in late-game fights.