Read it first, otherwise the movie will ruin your imagination.
No matter what, I think I'd always have to agree with that.
I have seen the movies first (in the cinema, when they ran in Taiwan, luckily in Japanese with Chinese
and English subtitles) and have the first three DVDs of the TV series ordered and on their way. I thought the movies are o.k., but maybe just because I didn't know what the source material was like. Looking forward to see the anime soon, although I'll have to take it slowly, as they'll take their time releasing the whole series...