They were correct.
Shaun of the Dead is a weird Rom Zom Com. A Rom Com with Zombies in it. It's not really a horror movie, which is good since I don't really like horror movies, but it's not a straight up Rom Com either.
It's definitely in the vein of the Hot Fuzz and The World's End which are part of this (very) loose trilogy of movies.
I liked it a lot more than I remembered from my first watch. I think going into knowing what it was helped a lot. The first time I basically watched the movie knowing nothing about it. This time I could just appreciate it for what it is instead of what I thought it might be.