I have been an Assassin's Creed fan since Black Flag. Completed that three times, Rogue, Unity, Syndicate, Origins twice, Odyssey twice, Valhalla, Mirage and Liberation HD. I can't imagine the combat and gameplay being worse for me than Unity, Valhalla and Mirage so that's how I can make up my mind already. I simply love Assassin's Creed for the most part with Black Flag, Origins, Odyssey, Rogue and Syndicate being my top 5. As long as Shadows is better for me than the other four games that are not in my top 5, I will be happy.
I also look at Assassin's Creed as a guilty pleasure. While not all of them are at the same level for me, I do love it when a new AC game is coming. Take Black Flag, Origins and Odyssey for example, I love these three games and want to play through them 100% again including the expansions. Everyone has games that they love and just "hit" differently than others. For some, it's Sony's games or souls games or Rockstar or whoever. For me, it's Assassin's fucking Creed baby!!!