Okay I will be the first to admit I have only seen the first 3 Swan Princess films at least 5 years ago, but just by looking at the trailer I can tell you the CGI animation is awful against the original, which you can see on youtube for a comparison. Bad animation really puts me off watching the feature. While the first one had beautiful animation, and great songs, this looks and sounds awful. Stick to the original, and ignore the other two sequels as despite the good animation, there is no evolution to the story- Odette turns into a swan and Prince Derek and Odette's animal friends help get her back to human form.
Personally I wouldn't waste your money on a obvious Christmas gimmick.