I'll say it straight, I love this game. I've played Onimusha's from 1-3 and Dawn of Dreams and it's by far one of my favourite game series, with Onimusha 3 being arguably the best in the bunch... For the PS2 anyway.
With that said, this port is one of THE worst ports I have ever seen, and because it's a port of a game I really like it just feels like a slap in the face when I play it. The resolution is low by default and can't be changed for anything else but fullscreen (understandable for a game this old, but the fullscreen looks horrible if you have a widescreen), there's no way to rebind the controls (there's a "configure input" selection in the options menu, but it doesn't do anything) and there's no way besides trial and error to tell which keys do what because the game reuses the keymappings from the PS2 version of the game (eg. "push R1+X to fire arrows" or "use the right analog stick to swap targets"... yeah, thanks). It's a downright mess.
If you REALLY need to get this game, if you ABSOLUTELY have to play it, then I suggest getting a PS2 and a copy of this game for that. It may be more expensive, but this port sure isn't helping the situation. I just feel like this PC port shouldn't be played. I mean, ok, some of the issues can be fixed through some complicated file editing or third-party programs, tools etc., but that's not the point. If this was a good port, none of that would be necessary. You should be able to play the game WITHOUT resorting to editing files or completely relying on third-party stuff. And even after you're done with all that complicated stuff, you still need to figure out and memorize the overly complicated and completely bonkers keymappings which, need I remind you, cannot be rebound. Some say that their gamepads work well with the game, while others, including myself, cannot even get the damn thing to work, which means we have to rely on JoyToKey and STILL have to figure out the damn keymapping.
Seriously, that is just way too much stuff to do to actually enjoy a crappy port of a good game. It's just not worth it.