Quite simply one of the best movies ever (of the genre).

The special effects are great.

The story is great.

The acting is great.

The characters are great (and very believable), which make you really care about what happens to them.

Most movies at the grosser end of the horror genre (including Cronenbergs) usually have such poor characterisation that I simply don't care about what happens to them - this movie is very different.

Probably Cronenbergs masterpiece.