Rating: 7/10 - Good fun
Once Upon a Time in Mexico is a good movie. It's worth the price of admission. But unfortunately it's the third movie in a series started by El Mariachi and Desperado. The two prior movies are brilliant pieces of film making, so in comparision Once Upon a Time in Mexico comes across as weak.
El Mariachi is a suprisingly good action movie shot on an impossibly small budget of several thousand dollars. It manages to keep a very real, gritty feel that Hollywood films typically lack.
Desperado, on the other hand, is possibly the most pure action movie ever. It was well polished and tightly editted. The only slow moments are when the director successfully emphases the hot, slow nature of the surroundings.
In both movies the main character's name never comes up. It's not avoided, it just never comes up. You're sure throughout that he has a name, we just never hear it said. Characters either don't know his name (and thus refer to him simply as The Mariachi in the same way you might refer to The One-Armed Man), or are familiar enough that names aren't necessary. As a result the main character is a sort of everyman. It doesn't feel contrived at all. In Once Upon a Time our hero is explicitly labelled El Mariachi, with an emphasis on the El. It comes across as a bit artificial.
Adding to the artificial feel is the decision to have the Mariachi's love be murdered prior to the start of the movie. Just like the beginning of Desperado. Apparently El leaves a trail of murdered lovers behind him. But this time his daughter died too, so I guess it's more serious.
The movie is a big mess. There are a pile of characters, at least eight major ones by my count (Sands, El Mariachi, Marquez, the president, the drug lord, the police woman, Carolina, and Jorge). This is ignoring the many other significant characters (The president's aide, Dr. Guevera, Sands' thug, the drug lord's American second, and the little kid come to mind) That's way too many significant characters for an action movie. As a result we jump around almost at random from character to character. Most of the characters never get enough time to be developed in any way. Everyone is a thin veneer of personality. It's just a bunch of scenes jumbled together. Fortunately most of the scenes are quite entertaining.
Strangely enough the main character is clearly not El Mariachi. He's just a brooding fellow who kills people. No, the real protagonist is Sands the CIA agent. Fortunately Johnny Depp again proves his skill as an actor. You don't see Depp, you see Sands, the slightly irrational, flamboyent CIA agent. His performance is the highlight of the movie.
It's a fun, slightly goofy action movie and probably worth seeing. But for the real treat, check out the prior two movies El Mariachi, and Desperado. There is a DVD available with both that includes some fascinating discussion of how El Mariachi was shot so cheaply.