Well, I haven't tried it, but word from people who have played the Japanese version is that a large portion of the game is almost exactly like Okami. Like, the first few hours are literally ripped right from the first game. It opens a bit after that, but still features all the exact same characters, enemies, and locations for the most part.
I'm kind of thinking of skipping it and just playing through Okami for the second time (finally...I've tried a couple of times and always get distracted). Sadly, no PS2, but I think I can do it with emulation.