After watching Phantasm, I liked it enough that I think I'll watch at least one of the sequels. There were a few things about it that really bug me in horror movies, but if I overlook those things it was a pretty good film. Zombies don't really play a large role in the film, so it is kind of weak as a zombie film, but I'm going to try and rate it on it's own merits.
The story is about a young boy, Mike, who discovers that the local undertaker, known only as the Tall Man, is not what he seems, and is taking dead bodies and using them to create undead slaves. He persuades his older brother Jody and his brother's friend Reggie, an ice cream man, that there is something going on, and the three set out to stop the Tall Man.
The music in the film is creepy, and the effects are pretty good. The Tall Man has this silver sphere that flies around imbedding itself in people's foreheads, and there are a couple of good scenes with that. The movie starts with a bang (no pun intended, for those that have seen it), and the plot moves along well after that.
On the flip side, there are a lot of elements in the movie that are never explained. Director and writer Don Coscarelli makes a very surreal film, and many of the images he presents seem to be thrown in simply to make the film weirder. It works, but if you're analytical like me, you will keep wondering about it. The Tall Man has the ability to become a young, attractive, blonde woman to lure his prey, and it's never really clear how. The purpose of the flying silver sphere never becomes clear either (other than to imbed itself in people's heads).
In addition, the characters alternate between cleverness and stupidity, depending on the needs of the plot at that moment. Again, some horror film viewers are OK with that, and Coscarelli does not do it that much.
There were some interesting references to other stories. There is one scene where the young boy learns a lesson by sticking his hand in a box and "overcoming his fear". This movie came out before the movie Dune did, but that may have been a nod to the book.
Overall, I would say give this film a try. It's really pretty good, if you can overlook a few flaws.