Confession: I actually like Foxcaflowne opening a lot. Is the original opening still superior? I want to say "Yes" out of fannish loyalty, but honestly, I think it's an apples and oranges case. That is, both openings set out to capture certain, different aspects of the series. In the case of the original Japanese version, it's the enchanting and romantic side. In the Foxcaflowne version, it's the dramatic and intense. Neither necessarily betray the overall tone of the series--drama, wonder, action, and romance are all vital elements of Escaflowne, and all elements would be difficult to successfully cram into an opening. So, I have a fondness for both.
As for the manga, stacked alongside the TV series it's awful. Stacked alongside the (beautiful but flawed) movie it's still awful. On its own merits--free of comparison to other continuities--it's merely okay. Due to its brisk pacing it's a pretty forgettable read, with a lot of once major characters fading in the background, dramatic conflicts with less than thrilling resolution, limited character interaction, and...yeah, I don't recommend it. I gave it a chance out of curiosity, and because my library carried the whole series, but I won't be preparing for a reread any time soon.
It's also worth mentioning that it's the only continuity where Van and Hitomi kiss. How messed up is that?