The 9th season of Stargate introduced a new enemy that was a nice inversion of the Goa’uld. Whereupon the Goa’uld had been aliens that played at being gods to control the galaxy, the Ori where pretty much evil gods. So, the old tactic of trying to get people to see the grand illusion of fake godhood wasn’t working anymore: it’s much easier to convince people not to believe in fake gods whose powers are technological instead of stopping people to bow to real gods who are secretly evil.
That said, despite the interesting setup for the last two seasons and the concluding movie The Ark of Truth, there were a few problems. They brought in the main actor from Farscape to replace Richard Dean Anderson as teamleader of SG1, which I had hoped would be taken over by Amanda Tapping (which would have been the natural choice and made more sense than bringing in an outsider). Then there was the Lucian Alliance. The whole space smugglers/drug lords angle just didn’t make much sense in the setting and felt like they wanted to introduce them for the hell of it without having thought this through. A faction that used leftover Goa’uld tech to actively grasp power after their defeat would have made more sense than interstellar drug barons when there’s no overarching economy in place.
Also, the entire conflict with the Ori rivaled the conflict with the Goa’uld, yet due to the limited space of two seasons felt highly compressed and at the end cut short. The Ori went out pretty much with a whimper and nobody was even sure until the last movie whether they had perished at all. The Ori story arc is by no means bad, but in comparison with the preceding Goa’uld arc feels just like a short addendum than the epic conflict it should have been. At least The Ark of Truth finished the story arc in a satisfying matter.