The first movie always seemed out-of-canon with the rest of the CardCaptor Sakura universe, IMO. It's supposed to take place between episodes 35 and 36, but Syaoran acts completely OoC. He's already developed a pretty obvious crush on Sakura by this point, yet it's not featured anywhere in the movie. If it'd taken place between, say, episodes 25 and 26, I could understand, but it didn't. I also thought the plot was a bit... meh. Clow Reed had some crazy fangirl who goes on a murderous rampage to find him? It's a bit out of nowhere, isn't it? >_>
One good thing about that movie, though, is that you get to see Syaoran's family. They sure are... unique. XD I also like that Nelvana actually gave the option between the Japanese version with subtitles and their butched dub. If they'd done that with the main series, there wouldn't be so much hate for them...