Fans of the manga may have issues with the story, but since I don't know the source material, it didn't bother me.
The key moments are well done, but in between those key moments things tend to drag on. I understand these are manga characters, so they tend to be on the unrealistic side. But something just feels off in the delivery of the dialogs, they seemed... disconnected. But once I got to those key moments I was thoroughly entertained.
The fights are fantasy style katana combat, but very creative and well choreographed. As a fan of martial arts movies, I enjoyed them very much. The "final boss fight" was fantastic and worthy of the climax of the trilogy. Bravo.
If you like action, especially martial arts action, I say this trilogy is worth a watch, but just keep in mind this came from comic books. As with most action movies, if you look too deep everything falls apart, so just sit back and enjoy.