While many call Zombieland a Shaun of the Dead knock-off, I believe this is not the case. While they are both zom-coms, which, I will admit, is a very rarely used genre, the similarities end there.
Shaun of the Dead is actively a spoof of zombie films, poking fun at zombie apocalypses while keeping the action silly and slapstick. Zombieland on the other hand, often has both poignant and serious scenes.
Zombieland has a fantastic cast - the very likable Jesse Eisenberg shines as usual, and his friendships with the 3 other survivors are very genuine. Woody Harrelson is perfectly cast, as is Emma Stone as the beautiful, mysterious Wichita.
Overall, while this may have come after Shaun of the Dead, it does not try to copy in any way. Although not as funny as Shaun, because of its likable cast and brilliantly shot action scenes, Zombieland is the film I find myself coming back to when in the mood for a Zombie comedy.