These comments assume people will have watched the original 'Cardcaptor Sakura' so will be familiar with the characters and the magical cards Sakura has collected. Watching this without watching the original might be rather confusing.
This series, made several years after the original, is set immediately after that original. Following a strange dream all of Sakura's cards turn clear and no longer work and her magical staff has changed. Once again strange things happen; the work of a new set of cards... the clear cards. With the help of her friends Sakura begins collecting these cards. The dreams continue; it would appear that Sakura's increasing powers haven't gone unnoticed.
I must admit I came to 'Cardcaptor Sakura' rather late but as an anime fan I wanted to watch this classic. I enjoyed the original and found this to be just as much fun. I like the fact that even though it was made twenty years later the makers didn't find it necessary to 'improve' character designs; this means one can watch this straight after the original without thinking it is too different. That isn't to say there are no changes... the cards, which are still similar in basic design, look great. The animation is also impressive. The ending does leave questions unanswered so hopefully we will get more in future. Overall I'd certainly recommend this to fans of the original; it was great seeing all the old characters back in a new story, which also introduces some new characters.
These comments are based on watching the series in Japanese with English subtitles.