I didn't even know they were still making Samurai Warriors games. I've only ever played the first one.
This may be a minor thing to complain about, but why must they place the dialogue text in the middle of the screen during battles? Warriors games have always been very chatty, so there's just this fat, solid dialogue box covering up the action in the middle of the screen for a majority of the time. Again, perhaps I'm just nitpicking, but there's better real estate that they could put it such as the top left or bottom right corners. I don't know why it's bothering me now as I would imagine this isn't the first warriors game that's had it.
After looking at some DW:8 gameplay, it doesn't seem as egregious as the dialogue box isn't so centered as it is here.
Anyway, the dual character thing intrigues me the most. Does the other character follow you around like your guards did in DW:(4?), or does it go off into other areas of the battlefield? I also wonder if you can set the AI character to clear out a specific area or if it's totally independent until you switch to it. How would it work with Coop? I never played SW on 3DS so I'm not familiar with the system.