Being lucky enough to be able to read in the original Spanish, I've sometimes been dissapointed by english translations - the smooth flow and colorful aliteration becomes stilted and awkward. I think the translator has to be almost as good of a poet as the original in order for the translations to work.

I guess that's why Spanish is called a "Romance Language" ;)

One of my favorites is "Love Sonnet XVII" - here is the first stanza:

No te amo como si fueras rosa de sal, topacio
o flecha de claveles que propagan el fuego:
te amo como se aman ciertas cosas oscuras,
secretamente, entre la sombra y el alma.

I do not love you as if you were rose quartz, or topaz
or the scarlet arrow shot by the fire.
I love you as certain dark things are to be loved,
in secret, between the shadow and the soul.