I thought the whole time-travel thing was gonna suck, but it turned out to be very well-done. There was one completely irrational story-related part involving Samanosuke at the end, but other than that, it worked out very well. I actually liked Reno's dubbed VA work better than his own real voice.
The game mechanics are exactly the same as in the first two Onimusha games, so if you've played them, then there's no need to read the manual. The only difference is that now you have to level up all the weapons and armor of two people instead of just one, which adds some time. Some of the enemies are more annoying than in previous Oni games, like those b*stard floating things that suck all your magic away, or those demon dogs that swat your ass, and once you get back up, swat your ass again. It also takes too long to get back up or access items in critical moments, which did cause me to die a couple of times.
Graphically, it ditches pre-rendered environments for a DMC-type 3-D one that only moves as you move, with no real camera control. It didn't bother me, since it was well-done and very comparable to the level of detail found in the 2-D environments.