I've seen the true face of the things you call Life the song of the siren that holds your desires but Death, she is cunning, and clever as hell and she'll eat you alive
Remarks about the translation
Death is personified here as a "female" hence the word "she". The siren is a mythical creature not the buzzer >> http://en.wikipedia.org/wiki/Siren
Very very hard to translate since Death is explicitly male in Greek, and you can't turn it into a female as required. My fifty cents:
Maybe instead of διατηÏεί it would be better to use κÏατά because the Sirens were actually "grasping" your desires to keep you with them. ΔιατηÏεί means "preserves". I don't think this conveys the meaning at all.
Instead of "Ï€Ïαγματικό Ï€Ïόσωπο", "αληθινό Ï€Ïόσωπο" sounds much better in Greek and is a phrase that we actually use.
"παÏά το Θάνατο" seems wrong here. I'm pretty sure that there is an implied period after "desires" in the poem. So I would start the third line as "αλλά ο Θάνατος"
"εξυπνος σαν κόλαση" doesn't make sense in Greek. "Clever as hell" is like "he is crazy clever" so I would go for "Ï„Ïελά Îξυπνος". Yes it sounds silly in a Greek poem, while it's acceptable in English but I'm not sure how to convey the exaggeration in another way. Oh and if you change the start of this line, you should also remove "που".