This is no classic, but it's a perfectly entertaining way to spend 103 minutes. It's definitely the best Canadian horror flick I've ever seen (actually, it might be the only one).
Seriously though, while the acting might not be Oscar caliber, it ranges from not offensively bad (Eve) to actually pretty good (Baker). And while a lot of movies in this sub-genre are full of characters you can't wait to see die (I'm looking at you, "The Breed"), I found myself rooting for the survival of a few in this one.
Sure, the premise of a group of young people stuck in a remote area battling evil has been done a million times, but that's because it's a fun horror sub-genre, and this is a decent entry. I really don't understand the confusion over the plot that many reviewers have mentioned--this is not a thinking man's movie and requires only a very basic level of consciousness to get it.
One last thing... I liked the ending! As I said before, if you're looking for a cinematic masterpiece, you'll be disappointed in "Dead Mary," but what are you doing in the horror section in the first place? If you're looking for a bit of mindless entertainment, "Dead Mary" will do the job.