It's a sequel to Donnie Darko only in that 20th Century Fox owned the rights to Donnie Darko after Newmarket Films went under, and the movie shares one actress, Daveigh Chase, who played the little sister in the original.
First the good: it could have been worse. I got the feeling that Director Chris Fisher really tried to create the same trippy, psychedelic feel as the first one. The soundtrack is excellent. Some of the scenes are legitimately creepy and well done.
But alas, without talented actors, this movie never really had a chance. Whereas Donnie Darko had some real talent in the Gyllenhaals (and Patrick Swayze in a great bit role), S. Darko has a bunch of "up and comers." Though pretty, Chase is not strong enough to carry the movie by herself, and nobody else really steps up.
If I had known before watching that S. Darko did not share any of the characters or director with the original, I wouldn't have watched it. I guess I could have looked this stuff up.