I thought Shinkenger did fine in almost every department, sure they could've done a lot more, but what series has done well since the new millennium. I don't anything about the, "Samurai Way," but from my knowledge, they touched that aspect enough for kids to understand.
As for Keisuke's acting, I never noticed, and thought he did a good job. Compared to the American versions of Super Sentai, Super Sentai is on another level of acting, as the American versions come off so off key and just out of place.
Some things I didn't like was the addition of the "Real Shiba 18th Head," it was so late in the series, but I understood why they did it. However, Tanba made me want to just go to my T.V. and wish that I could smack a good one to knock him out till the end. Having such a big secret and a huge impact was kinda reminiscent of the past Super Sentai's. Thank goodness no one died in this series!!
Hiroki did a great job as Ryuunosuke, the character was funny and annoying, which was kinda weird for me because I wasn't used to seeing Hiroki in such a different role. He's usually the stoic and calm type in the movies and shows I've seen him in.