I have read all the negative comments before posting this, having just finished the series. I have played the game, which this first season was based on, so I can understand that a lot of the comments are it's not exactly like the story in the game"..
Some people can never be happy. For me the series did lack decent combat scenes until maybe the last episode where I think it was actually at its peak. If you want the exact story from the games then go play the games because it's a show and if you copy it dialogue for dialogue then it's going to be predictable.
Kiryu I felt could have been more of a hard man we only saw it in brief spells. I was happy with the casting I thought each character portrayed the roles well. I would of liked to seen more scenes with gorijama and kiryu. I'm giving it 5 stars because I want them to make more I love the world and hope they continue the series. I'm going to say I was satisfied even if it was a slow start.