As the age old saying goes "Too many warriors spoil the cross-over fighting broth".
Because of this I feel immediately biased towards Orochi, I mean it's the same but with even more overly powerful warriors to choose from. And surely bigger means better right. Right?
In this case it's wrong, for me the key reasons I liked DW4 have been blurred somewhat. The storyline in Orochi is bad to the core - random characters thrown in at all times, there's so many of them the majority are reduced to bit parts. The story does not make me even want to progress further as it feels so tacked on. The novel concept of combining two worlds would require some kind of incoherent plot, granted, but I feel like I deserved better than a story driven by dialogue scenes alone (I've bought enough of the series sequels to feel a bit cheated!!!).
Also, the action is completely the same; instead of going forward like the Empire spin-offs do by applying a bit of strategy Orochi plums for the same mundane hack-n-slash affair. Yes, you're part of a huge army but it seems like you're the only person doing anything, I remember on several occasions an officer begging for help as he/she is facing overwhelming numbers to then reach them and discover they're actually up against about five soldiers.
Unfortunately for the repetitive action of Orochi a butt-load of characters does not go in they're favor. Eventually all characters feel the same, whether they're wielding a sword, spear or fan it doesn't matter after a while.
However, for me the score of six is for one reason alone: Progression.
I love unlocking new characters and weapons and even more so I adore leveling anything up. Hell I'd play a game about knitting if I could level up in ability (Cool, I'm level five in cross-hatching now!). So the idea of having seventy plus vessels to level to ninety-nine is a guilty pleasure for me, even if it means having to play as Meng Huo and his annoying wife for a while.
So, in conclusion, if you know you're going to like it as you've played all or any of the others then get it. For anyone else I'm recommend trying one of the Dynasty/Samurai Warriors efforts first, otherwise the game won't make any sense at all.