Great
Good:
-The music. Very well selection of music and remixes.
-The animation. Well, it's not the best, but it is FAR from bad. Hopefully this will get better with new episodes.
-How the zombies looked. They looked kickass.
Bad:
-The voice acting. Well, not a lot of complaints here. Just change Toadsworth's voice, cuz he sounds like a teenager with a sore throat(no offense), and the voices were a bit quiet. Also get itallian people to do Mario and Luigi's voice.
-Characters were out of character. Luigi should be a pussy(like when Mario asked if they agreed, Luigi should've been hesitant), Peach, well, I personally liked how she was all kickass, but it isn't like her.
-The backstory. There barely was any backstory at all. But the story itself was okay.
-How the zombies looked. Their eyes are gradient. I know this is trying to show us it's glowing, but it just isn't working. Also, add more movement to them please. And flesh wounds(I know that this is the first episode, so I won't take any stars off).