Anyone with a negative review, obviously didn't finish the series.
Spoilers
I knew Plagueis was going to appear eventually along with Yoda. And for the people saying Maul was the first sith in "modern time" this isn't set in modern time, it's 100 years before phantom menace.
I also want to express your doubts in Ki Adi Mundis character ark. Go youtube why this works. Learn a thing or two from a simple search. Stop acting like you know what star wars is. Figure out the difference between Canon and Legend.