There are issues. The level at which those issues affected your opinion of the movie depends entirely of how highly you regard the original, but:
1- They tried to change the genre of the series, from space opera adventure to science fiction. That is the reason why most people hated midiclorians.
2- They overused the green screen, to the point where everything looks fake. Interior shots, exteriors, conversations, monologues, characters, vehicles, fights, everything was shot in green screens. In some cases in understandable, but in others is overkill. If you could see them without the effects, all you could see 99% of the time would be people on wires mimicking in front of green walls. Speaking of which:
3- Acting is uneven at best and atrocious at worst. Some actors like young Anakin can't act, and others stumbled a lot with the asinine dialogue Lucas throw at them. Which reminds me:
4- Lucas can be a fairly good director, but he is lousy as a writer. Most of the dialogue comes out unnatural and awkward, and potentially emotional scenes come out as laughable. Which reminds me:
5- The love scenes... god! The love scenes. They are among the worst love scenes I have seen in my life. There are better scenes in any J-Lo flick, or Twilight. Two bricks have more chemistry than those two; and the scene when they are rolling in the field almost makes me puke. But the worst part is:
6- Its a movie made by marketers, which is worst than a movie made by concensus or a movie made by executives. There are entire sections, characters, lines or scenes that where there just to sell toys of it. Do you know why Jar Jar Binks appears in all the sequels, despite everyone hating him? Because Lucas saw that small kids responded positively to it. Do you know why there are 30 minutes of race in the first one that looks nice but leads nowhere? Because they wanted to sell you the toys (there are even videogames out of that single section). Did you see that small robot Anakin chooses to stand on the lava instead of, I don't know, a rock? Or the dozens Jedis that fight in the giant coliseum, which are not even named? Or each of the different creatures and vehicles? There are toys of those too, each sold separately.
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