In Modern Greek it is pronounced "DHEDH-ah-los"("dh" representing the th sound of "then" rather than that of "think"). In Ancient Greek it was pronounced "DIED-ah-los."
A very unusual name. I feel like these names from Greek and Roman times would sound weird in today's modernized world. I'm unsure about this being used as a first name. I hear this and think about the Icarus and Daedalus story.
Stephen Dedalus is the protagonist of James Joyce's semi-autobiographical "A Portrait of the Artist as a Young Man". He seems to be a general alter-ego of the writer, and appears in many of Joyce's works.