Or more specifically, what's with its generally mediocre results in terms of visuals and performance in actual games?
I've seen some almost photo-real renders created with it, yet I struggle to think of any really impressive examples of it in an actual game. Seems almost every time I read that a game's made in Unity, I could've guessed just from the meh graphics and wonky framerate.
I mean, games like Yooka Laylee 1 and Impossible Lair or Panzer Dragon Remake look and run quite nicely, but they're not pushing any limits.
With other modern engines like Unreal, id Tech, Snowdrop, Cryengine, Frostbite, etc I can think of multiple showcase games.