A lot of fun.

Pretty good movie overall. First half was nothing special but it got better as it went along.

There is, somehow, an interesting story here, as well as some good acting. There are also some good scenes

Watching it is like watching the spectacle of a class clown at their best: you laugh at their jokes, instigate their defiance, and "ooooh" when they get in trouble.

I don't know why this one hasn't been watched or reviewed more. It created a good air of paranoia, and mystery. State-of-the-art tech, excellent acting, fine screenplay- what the heck more do you want?! Is it just because it's from Mexico? I suspect a conspiracy, just like poor Doc Alexanderson did, and if you saw this, you know what happened to him... Black helicopters, best friend killed, trusted colleague murdered, etc... Good God! I can see the black helicopters coming for me now! Really? Just because I gave an ignored Mexican movie a great rating and a good review? Alright, I take it back- it stunk. Now, please give me back my dog!

The only thing I won't really agree on with the other reviewer of this movie here on IMDb, is that I do think there a quite a few Spanish movies with good quality. As I enjoyed this one, I do have some other great movies that I like (REC and Nameless just to name one directors CV). But this little gem is worth watching too.While it does start off pretty bog standard, it does turn into something different. Quite different as you will experience. I'm sure it won't be to everyones taste and it won't really be commercially successful, but you have to admire the screen writing skills of the guys at hand here. While there are a few flaws here and there, the overall punch is not diminished by anything. If you like your movies to dare you and give you complex things to think about, this is for you

You can tell by watching this movie that so much thought and work are behind the international production. The script is thoughtful, with a storyline full of turns and twists. The casting was well done with actors well suited for the role. I will recommend to all my friends, as it is both complex and keeps you interested. Its rare to see such good quality film in Spanish, and also, its genre as a thriller is also rare in Spanish language movies. If you want to see a unique thriller movie that will entertain you, this is a very good choice. This is one of those movies that you can't guess what will happen from beginning to end, unlike many movies out there today. I also think the movie length is well balanced, not too long or short for the story that is told.