Opinions on this film vary. Die-hard Cronenberg fans sometimes find eXistenZ to be a little lightweight. Especially when compared to more provocative films like Crash or depressing films like Spider or Dead Ringers.
On the other end of the spectrum, those unfamiliar with Cronenberg's work may find this movie to be too bizarre!
I won't talk too much about the plot, as other reviewers are better at it than I am, but I'll say that it's kind of a game within a game within a game (within a game?). Like a few other films of the day it explores the nature of reality (The Matrix of course is most popular).
eXistenZ was actually Cronenberg's biggest budget at 25 million (not including his current project A History of Violence). The special effects are fantastic, and there are some good moments of gore. A couple people get shot in and around the face. Yes, this is a return to his past in many ways, though again, in a slightly more playful manner.
There's plenty of extras on the DVD, most notably three separate commentaries and a long (almost an hour, I think) feature about production designer Carol Spier which mostly focuses on eXistenZ but also touches on some of her earlier work with Cronenberg.
Definitely worth getting, and an especially good introduction to Cronenberg's work (before moving on to more disturbing pictures like Videodrome and The Brood, and more slow, paced pictures such as Spider and Crash).
Believe it or not, seeing a guy getting his face blown in half by a gun firing human teeth and people porting into a game system that looks like a bizarre fleshy body part is rather tame for Cronenberg. Certainly a lot easier to watch than the flesh-eating puke in "The Fly" or drinking fluid out of a fleshy straw on a large bug's head in "Naked Lunch".
One of the reasons I enjoyed this film was it reminded of the mind-bending plot twists of a really good Philip K. Dick story. By the film's end you have no idea what, if anything, is real and not just a game.
Some reviewers found the performances very weak. But often, this is done deliberately: one character named D'arcy Nader is played so cartoonishly that the main character, played by Jennifer Jason Leigh, comments on how lousy his dialogue and accent were. Personally, I thought the two lead performances were very good. Leigh gives this picture her all playing a sexy game designer whose whole life revolves around this virtual world she has created. Jude Law is also very good, especially his humorous reactions to all the weird stuff that happens around him.
This picture is particulalrly entertaining if you've ever played a role-playing computer and are familiar with the "game loop" that computer characters go into when you're not speaking to them.
The movie also makes a very strong comment on how video games have de-sensitized us. In one scene Jennifer Jason Leigh shoots a character dead just because she didn't like him, but then she can't figure out if she killed him for real or just in the game. a brilliant comment about seperating fantasy and reality.
This is a very well crafted, highly underrated movie. Possibly the most intriguing science-fiction film of the decade.