Right, Warriors Orochi 2 is a fan service. Only fans want this game and fan die-hardness covers the flaws.
The Bad: Admittedly it is repetative and won't appeal to anyone unfamiliar with the series.
I say simple button mashing fun because that's what this game boils down to, and personally I think it's great. There is too much pressure to produce games that have easy-to-grasp yet complex control systems and Koei is right to keep it's controls simple and familiar. The graphics are a touch off but they always have been in the Warriors series so again there is familiarity for fans. The soundtrack is lifted from previous games and is a rather nostalgic touch.
There is much content to unlock in the form of extra stages, high power weapons and gallery art that doubles as your main menu background. The action is solid and the fun to be had co-op or single player is satisfyingly old-school. This series is a relic of a game that was given a breath of fresh air for Dynasty Warriors 6 and a nice return the classic format in the two Orochi games. I think that if you like the series then the game continue to deliver. The reviews i've read say that the series fails to try a new method or engine and as such it is not a prime example of a game.
The main sticking point for reviewers is the repetativeness of the game. Well I ask What game is not repetative? The answer is none. The reason is simply this: In shooters you go from point A to point B and kill all enemies en route, Racing games is pick a car and roar around a set number of tracks, RPG's fail here too on relying on the retrieve such item or kill specified enemy. The point is even if you never repeat the same task twice in a game if you ever play it again: repetition.
My final point is simple: If you are a fan you should buy this game, if not then don't as you probably will not be swayed by the premise or story.