The short introductions for each plays are sufficient to help the reader's appreciation, but not too long to be off-putting. I suppose perhaps even a little too short.
Paul Roche's translations are very good: readable and often preserving elements of the original Greek. Pay attention to his footnotes, though, since that is where he notes problem lines and/or his own interpolations (in particular in the Bacchae).I found his introductions not particularly useful, an...