Here on Shmoop, we're using the translation of Prometheus Bound by Alan H. Sommerstein. This translation has a lot of great things going for it. For one thing, it's extremely clear. Actually, you could say it's a little too clear. One thing this translation doesn't show us is that most of the dialogue in the play is in verse, not prose. (Sommerstein only slips into verse when the Chorus is singing, or when other characters, such as Io, are going a little crazy.)
The play is also full of bizarre and unexpected poetic turns of phrase. For example, when Hephaestus is chaining Prometheus to the rock, he doesn't just tell him, "This is really not going to be fun, he says:
[…] welcome to you will be Night of the gaudy apparel when she hides the daylight, but welcome too the return of the sun to disperse the early morning frost. (23-25)
As Sommerstein explains in his footnote on p. 446, this means that "the coming of night will temporarily end one kind of suffering (from the sun) only to bring another (cold) from which, in turn, you will long for relief; and vice versa." You got all that?
But this crazy creative poetic stuff doesn't just seem to be a lot of frills and curlicues. In addition to making the language beautiful, it makes the play intense. If style were music, we're guessing that it would be a Bach fugue or a heavy metal guitar solo—or maybe a heavy metal guitar doing a Bach fugue.