Review:
It gets Buenos Aires geography about 80% right, the characters don't sound mexican, and there's only two or three phrases with mismatched genders.
This may appear to be faint praise, but trust me, it's head and shoulders above the average non-argentinian fiction in that respect, including (specially!) that written by other spanish-speaking writers.
The story itself is sort of thin, and lays the mystic "tango is a dark dance" way too thick, but that was to be expected just from the title.
I got this as a free PDF from Boing Boing, and it's not bad.