A nice episode, just when you think the Atlantis team finally finds the mother of all weapons/power source, you just have to wonder if this was just too good to be true. McKay was at his most arrogant in a way trying to justify his massive ego in trying to top the Ancients in their failures. So of course in the end they not only lose their newest discovery, but McKay and Sheppard barely gets out alive with help of the Daedalus providing cover in a cool CGI sequence. Finally when Dr. Weir was yelling at McKay, I would've never expected McKay's ego to further place himself in a worse spot by stating more of the solar system was destroyed rather than less.
Btw: Didn't the Ancients' space gun looks similar to the Tollan ion cannon?
For those that don't know what I mean: The Tollan were an advanced human group on the series SG-1 that were eventually wiped out by Anubis.