Ok, so I've played through all the characters in Ninety Nine Nights, and have a general idea of the game and its plot. While I haven't finished the quintessentially final mission in the game (Inphyy's Special Stage), I think I have played enough to form an opinion on it.
This game is a hack-and-slash genre game. Keep that in mind. For new gamers, I think it can be a fun experience, since it's relatively easy to learn and play. For gamers who are expecting the game to deliver something new or groundbreaking, it does deliver in one area, and that is in the sheer number of enemies that you face per level. You face literally thousands of enemies, and you have allies at your side to fight with you. While the A.I. isn't stellar, it really is the standard A.I. of most games of this type of genre. A.I. in these types of hack and slash games generally swarm your character and take a swing at you, but aren't that smart and don't really care if they will get hit. That's the idea, because the game's point is getting you to hit them all back. Your character can literally destroy all of them with the right combo attack.
The story in the game is very simple and straightforward. Don't expect a lot of twists and turns in it. If you were looking for story depth, you're in the wrong place, and you shouldn't pick up this game. But if you're looking for something to take out your daily frustrations on, N3 fits the bill quite nicely.
I'd give this game an 8/10. It gets a high score because of the presentation, particularly with the first three characters: Aspharr, Inphyy and Myifee. The rest just aren't as interesting. I'd recommend this game only if you're into hack-and-slash action. If you're expecting an RPG level experience with the story, this game isn't for you. If you're expecting Ninja Gaiden level of action gaming, the game isn't for you either, because combat is fairly straightforward and enemies have simplistic intelligence. If you want a fun romp that has decent longevity, this game fits the bill quite nicely. The Asian version in particular is a great buy since it's only 40 bucks. For gamers in Europe or the US, well, if you have the extra cash, the game is pretty good. If you can rent it, why not?
NOTE: One huge mistake made by the developer is not making Inphyy's Special Stage more obvious when it becomes available. Take note of this: Once you've finished Inphyy's regular campaign, save your game then DO NOT OVERWRITE THAT SAVE when you start on another character. Once you've finished all the characters, reload Inphyy's last save to find the real, last, secret level (called "Another World").
I can imagine a LOT of gamers did not find this 'special stage' at all, since the game doesn't even prompt you that you can access it. You also can't access it unless you reload your last Inphyy save. So remember, do not overwrite your gamesaves for N3....
NOTE 2: If you find the game too frustrating or the bosses too hard, learn to use the BLOCK button when the bosses hit you. The BLOCK button is the left trigger. Also, the 'STATUS' option in the PAUSE menu lets you equip items which should make your life easier.