I know that there was a lot of backlash when Tokyo Mew Mew was bought and released by 4Kids in America because it was changed dramatically. I haven't seen the English version of it, however. What was changed when it was brought to America?
I didn't watch it extensively, and I never had much contact with the original material, but here's what I remember.
The series name was changed to "Mew Mew Power". They did the usual character name changes; the main heroine Ichigo became "Zoey", Mint became "Corina", Lettuce became "Bridget", etc. You can see the full list here. The music was changed to American-style pop. As far as I know, there weren't extensive edits for content and the plot wasn't really changed, although some characters come off differently because of how the dialogue is written, or because of the way the American voice actors play them.