I'd say the movie was okay, but I wouldn't call it great and I'd hesitate to call it good. By Devlin-Emmerich (hope I got that right) standards it's a remarkably restrained film (possibly the most restrained they ever did?).
It's hard for me to recall seeing the film without having any knowledge of SG-1. There's some impressive scenes, but there's also a lot of stuff that can be a bit slow-going, especially if you're not familiar with SG-1 (i.e. why does any of this matter?).
If you're planning to watch the series anyway, I might recommend looking at the movie as the pilot episode. Which is, I suppose, a bit ironic as SG-1 itself has a pilot episode (two versions, in fact). With all the whackiness and occasional facepalming that that may imply.