Help me understand the AC Shadows hate, please

Like the title suggests, I'm genuinely curious about the hate for AC Shadows and would like someone to explain it to me. I've loosely followed the game's news so I'm out of the loop on it. Here's my big confusion: For years it seems AC fans have been asking for a game set in feudal Japan, and now we are finally getting that with Shadows. And yet everyone is hating on the game. Have I missed something about the game? Please someone kindly explain what's going on, thanks so much!