Shaun of the Dead is a silly zombie flick with strong undertone of seriousness. There's is no doubt that it is meant to make us laugh, but at the same time, it has a number of dramatic scenes. The couple story is the running thread, but it's not the meat on the bone.
Most scene are a comic setup never failing to have the audience roll back their eyes in incredulity. Toward the ends come the more dramatic ones, and those are the one who make you think.
The dialogs very real and flow at a good pace. The editing is done in a quick efficient manner. The story is very interesting. The zombie threat and its working are imaginative. The acting is good, Simon Pegg, Nick Frost, and Kate Ashfield giving us the best performances.
Overall, it's a very solid entertainment in brain dead way.
It's a must, if you don't mind zombies and a bit of gore.