Well, I finally got to watch the DVD movie, and my first take is that generally it was okay. I'm sure many will disagree with me, but I didn't think the movie was that great, I think I enjoyed the first movie, The Ark of Truth, more.
One of my problems is that I was just confused with how they handled alternate timelines (two Jacksons?) and the whole paradox thing. I couldn't find consistency at all, so in the end I just basically went with the flow and accepted whatever happened (like Cam, dad/grandpa Cam?) and tried not to rationalize things too much. Maybe Cam will be O'Neill's daddy. :)
There were good parts to the movie. I thought it was great how they got lots of the characters (system lords and SGC members) back into this movie. The special effects were nice, and seeing the fleet of motherships bear down on Earth was cool! While the plot of changing the past is old, there were some good stuff there, like Vala being Qetesh again and showing her treacherous ways. Ba'al was nice, too, and having Cliff Simon there is always great. I was hoping they'd use more of O'Neill, however, but at least Don Davis was there for his final performance as General Hammond.
Yet with all, I did have another big problem besides the alternate timeline issues: I didn't find the movie very exciting. There wasn't a lot of humor, there weren't many tense or dramatic moments, and the whole ending was somewhat anti-climactic. So while the special effects and the acting were fine, parts of the movie seemed to drag and the script or main plot was a bit lacking. Perhaps I'm being too harsh, especially since I've only watched it once, but I do hope that future stargate movies will continue with more interesting adventures, which this series had in abundance.