The Ark of Truth was the kind of satisfying finale to season 10 that I was hoping for. Great stuff - a lot of fun.
The Ark of Truth was well written and directed, and felt like a direct continuation of season 10. The actors continued to do what they do with these characters (which is a good thing), and the action was very good (although they've done better before). As for the special effects, I thought they were excellent (not $100 million budget excellent, but for a straight to DVD movie based on a cancelled TV series they were fantastic).
The only gripe I had about it was that they threw in everything but the kitchen sink (all of the prerequisite SG1 subplots were there). Paring it down and eliminating one of those subplots might have made the movie a little better (Sam and Teal'c don't get quite enough to do in the movie as a result), but as it is I still think it's a damned entertaining movie - as long as you've watched the last 10 years of SG1. If not, you're going to be lost.
Clearly, though, this was not made to win over new fans. This was made for the fans who have been following the show for the last decade. This was made for the fans who weren't happy about the Sci-Fi channel cancelling the show in a cost cutting move, and as one of those fans I am very glad they made this movie. I enjoyed the hell out of it.
Finally, the resolution of the story is what they've been setting up for the last two years of the series. No major surprises, but it was carried off very well.
For those familiar with the SG1 series (particularly seasons 9 & 10) The Ark of Truth is highly recommended. For anyone who has NOT seen seasons 9 & 10 of Stargate: SG1 I would advise holding off until you have seen those seasons to put everything in proper context.