I really like Scott Adkins but he's not a Ninja
The first film landed on a sour note for me. I love Adkin's acrobatics and his stylistic and dedicated martial arts skill. When he's in character as Yuri and says "I am the most complete fighter in the world", you believe it.
However, a complete fighter is not a ninja. There's a fundamental difference between the two and the way they approach combat, and in the first film I noticed Adkins was still...well...it was like a guy who was a really good martial artist who put on a ninja costume and not a trained assassin using all his auxiliary skills to come across as a complete ninja.
I don't want to say it, but it reminded me a bit of American Ninja with Michael Dudikoff.
Hopefully, they can get Adkins to portray a more deadly ninja in the sequel, closer to Tsuyoshi Ihara's portrayal of a very believable ninja in the first film.