Unplayable.
RDR: Undead Nightmare is a game to avoid mainly for three reasons:
1. The controls are tragedy.
Just try to make Marston to do what would seem as the easiest thing in the world, for example pass through the doorway of a house that happens to have three little stairs in front. Seriously it might take you half a minute or more, doing maneuvers until Marston positions himself exactly in front of the doorway, not an inch left, or right. I have seen big lorries making much less back and forth moves to park, than Marston needs to hit the door!
Also at some points it seems as if you don't have real control over Marston's speed. For no apparent reason, the moment that you desperately need to run, Marston walks like a snail. (and gets killed of course)
And don't get me started about the controls of the "zombie-horses" riding. It is so unresponsive that you might as well push the left stick at any direction randomly and you will still have better chances of getting your horse to move in your desired direction. I have played a lot of games in my life, both old school and modern ones, but frankly I haven't seen anything like that before.
2. Unfriendly game-play.
I never quite understood why you can shoot as many as 20 times at a zombie and still not die!...It's beyond comprehension. They only can be killed if you shoot them at the head. Okay. What would be more natural than reward the player that makes a successful headshot with an instant death of the zombie, and allow to the player that cannot find the target so easily, to still be able to kill the zombie after a certain amount of hits in the body. All shooting games rely on this principle, why Undead Nightmare to be the exception?
Also why do you need to get in all that trouble, just to be able to save your game? A save point is always a bed in a house, but very often you need to try different doors, climb stairs, walk through corridors, and generally get yourself lost in big houses, trying to spot the specific magic bed that can be used as a save point. You need the game's compass to find your save-point inside a house, seriously.
3. Bugs.
Another thing that I can't understand is why the game suddenly becomes so dark when you fight zombies in a cemetery? After a couple of unsuccessful tries to clear a cemetery during midnight time, (where I couldn't see absolutely anything), I tried to do the mission later in the light of the day. But again, after the cemetery sequence was initiated the game screen became dark again for no apparent reason! Is this happening only to make your life difficult, or is it a bug?
I also noticed that during midnight the interior spaces are brightly illuminated by the moon, but once you step outside you can't see a thing! As if the moon illuminates only interior spaces!
Last but not least: The game froze on me once, the moment exactly when I finished a difficult mission. Pure frustration, no need to expand. I have read in other forums that many players had the same problem. So even if it was a game worth playing, what's the point if you are not sure if you will make it to the save point, or the game will freeze.
It's a shame really for a game with so big potentials to end up offering a negative gaming experience.