It's hard to tell how much of this series finale was conceived after the decision to cancel the series. Is that final scene on the balcony something that was always on the page, or was it a last-minute addition to give the fans a sense of closure? Was Atlantis always intended to crash back to Earth as a cliffhanger?
I personally believe that the return to Earth was always on the books, and that we should be pretty damn happy that it was. Normally the seasons end with a cliffhanger, and ending the series that way would have been a shame. This choice makes it seem like the series has come full circle (recalling that "The Rising" began with the Atlantis taking flight in the distant past).
Of course, none of the long-term issues are resolved. This eliminates one particular problem by taking down the only Wraith ship with a ZPM. But Todd's alliance has fallen apart, the Wraith are still marauding the Pegasus Galaxy, and now one of the major human powers has flown the coop.
It's not hard to imagine that repairing and refining this "wormhole drive" will factor into any future return to Pegasus, and might even factor into the impending launch of "Stargate Universe". With the SGC and Atlantis in such close proximity, I also can't help but wonder if this was meant to facilitate some future character cross-pollination. With Area 51 gone and the defense of Earth now a rather big problem, Atlantis is going to be at the center of a great deal of attention.
Keeping Todd around was a great choice. Keeping Ronon alive may not have been. As much as I like the character, he hasn't been given much in the way of development of late. The producers only seem willing to take out major characters when they want to toss a cast member out of the franchise airlock, and this would have been a stunning change of pace. Hopefully the eventual TV-movie will give Ronon more to do to justify his survival.
As series finales go, this did pull out most of the stops. Sheppard and McKay had their usual moments of brilliance, the supporting cast was strong as ever, and Woolsey gave a rousing command performance. (Who would have guessed that Woolsey would be a better leader than Carter?) It was great to see some old, familiar faces here at the end. Some items felt a bit rushed at times, and this would have worked better as a two-hour finale event, but they did a great job with the time and resources available.
Perhaps the best thing I can say about this series finale is that it was much better than the series finale for "Stargate SG-1". That finale was simply frustrating; this episode did a nice job of bringing the series full circle while pointing to the future. Frankly, I feel there's more potential in further Atlantis adventures, considering how the two "SG-1" DVDs have covered off most of the lingering plot threads of that series. Hopefully it won't be a long wait before we discover what the future holds for Team Atlantis.