Magic Knight Rayearth follows the manga fairly closely. It is still definately about three girls who are summoned to another world by a beautiful princess in distress to save it from destruction, and it seems to have all the trappings of a great magical girl series. (If you wonder why I use "seems" check out the Triad Of the Moon's Magic Knight Rayearth page)
The dubbed version is excellent. The songs sound equally hideous and catchy in English as they do in Japanese. A lot of this may have to do with the fact that the original opening theme doesnt rhyme, so it was easy to keep the words the same in Englsih. In fact I prefere the dub over the sub, because the translation is better. This may sound insane, but it is very hard to watch a tape where you hear Hikaru calling "Umi-chan! Fuu-chan!" and the subtitles say "Umi-ster! Fuu-ster!" I think they could have found a better equivalant, like maybe having a cultural note, or translating it as "Dear Umi! Dear Fuu!" Also at one point Alcyone distinctly calls them "eggs from another world" I heard tamago, but they translated it as "Magic Knight fledglings". No big deal, but when you can hear the differance it is quite anoying.
The animation is a bit funky. The character designs were not done well and the eyes are just weird. The best looking character is the one that was never in the manga.
Despite the irrating animation glitches it a fun show to watch and has enough variation from the manga to seem new to people no matter how well they know the manga. Plus if you're a real Ferio and Fuu fan, there are some great mushy moments!