It is a must see, really! I usually hate Netflix productions or anime based on video games. But this one gives me the vibes of Basilisk first season (2nd was horrible, lol). Regrettably, I did not play any Onimusha games on PS2/3/4..etc! but a glance on gameplay on youtube, it shows the same concept and almost same zombie monsters. Each game had different protagonist, but in this anime, it is the legendary Musashi.
3D did not bother me, in fact, it is the best 3D with 2D line art converted to look old 2D style. Fight scenes are breathtaking and there is only one episode that felt like a filler (fighting the Yoshioka women, not really a fight) but it was short and very acceptable to show the underlying character development with dialogs.
I rate this 10/10 Perfect.
I seldom do that, I am usually generous with my ratings (1-5 for really bad ones, always 7-8 for all average ones, and 10 for the ones I really like. I reserve 9 for almost perfect ones)