Awesome Music: For a series that has weaponized sound and musical instruments, it is to be expected to have a lot. Kagayaki, the 1º opening, takes the cake.
Broken Base: The second half of the series. The general consensus seems to be that those who liked the mold-breaking approach of the first half disliked the second, but those who prefered the franchise's more traditional style prefers the second half over the first.
Epileptic Trees: Shuki, the third female Kamen Rider recognised by canon after Femme and L'arc, and the third to be killed off after an all-too-brief stint.
Tough Act to Follow: In-universe example - Zanki would like Todoroki to carry on his name after he dies, but Todoroki believes he can't ever equal Zanki, and chooses to keep his own name so that Zanki's legacy will remain untarnished.