This movie isn't as bad as everyone thinks it is, quite franquently I enjoyed it and thought it was pretty good. And yes I have watched the original series.
Eureka Seven The Movie is set in an alternate universe-meaning it's a completley different story, and characters have slightly different roles to play (like good guys are bad guys for example)-the film starts off with Renton as a young boy who is going off to see a Stardust flower (or something like that) bloom with his friend Eureka, their teacher Proffecor Dominic and a lava state creature Nirvash. Dominic tells them about how if you make a wish when a Stardust flower while it blooms then that wish might come true, Eureka attemps to make a wish but the flower fails to sucsesfuly bloom and dies. Dominic gives Renton and Eureka the seeds of the flower to use as good luck charms, and then leaves the next day to work on an experement. Soon after that some people come for Eureka take her away, and from that moment on Renton relise's that he can't protect the things that matter to him and vowes to one day bring Eureka back to where they grew up and protect her.
As I said erlier the story is completly seperate from the orginal series because it's set in an alternate universe-which I think is shame, but oh well-but even if it's not the continuation that everyone was hoping for, the story is still just as good as the original series's story.
The animation is also good and is almost the same as the series but in a few place's a bit better. The music is also the same as the original series, which is good because the soundtrack is quite good, espacily when it comes to the fight scenes, theres only one song in the entire movie that is new (as could tell) and that's the ending but all it is is just loud noise.
Overall this is a film that you will ever like or hate, depending on how much of a fan you are of the original series. If you want to try out the movie before watching the series then thats fine because they're completley seperate. Or if you're a fan then ignore all the reviews and watch it for your-self. This is a film for both new and old fans and I recomend it to anyone interested in it.