"Evil Dead 2: Dead by Dawn" is a comedy disguised as a blood-soaked shock-a-rama. It looks superficially like a routine horror movie, a vomitorium designed to separate callow teenagers from their lunch. But look a little closer and you'll realize that the movie is a fairly sophisticated satire. Level One viewers will say it's in bad taste. Level Two folks like myself will perceive that it is about bad taste. - Roger Ebert
Evil Dead II is a pretty critically acclaimed film, it's even in the top 500 films in the TSPDT poll, but it remains underrated.
There's a sense in which a movie like this can be endured only if you distance yourself from the material and appreciate its manipulation of the genre. It can be seen as dark (very dark) satire. Or, you can just throw up. - Roger Ebert