I thought it was a good episode, although not quite as strong as Question Authority. In terms of plot, writing and voice-acting, I'd put at the same level as last week, but something in the tempo or pacing seemed off. I agree it is mostly a set-up episode.
And as a supplement to Takyris's summary, my impression is that Luthor didn't just hack in after Waller called but that 1) he had infiltrated the JL computer some time ago (presumably in the Task Force X time frame), and 2) already had the targeting program running, and was waiting for Waller to call (correctly anticipating that she would have moved the Cadmus operation after the security breach) before initiating the fusion-beam.
Finally, fun dialog paraphrased from memory during a JL debate on whether to take out Cadmus:
Green Arrow: "Batman brought me in to keep you guys honest."
Superman: "Do I look like Batman?"
Flash: "Yeah, you kind of do. Especially when you get all scowly like that."
-RedShirt