These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Author Appeal: Rinoa is clearly Monty's favourite character. She gets an awesome re-design, several new and cool powers, she's canonically the most powerful female character of Team FF, and she gets the most artwork over on Monty's deviantART page..
Episode 3 was perhaps the biggest sticking point of the divide as it was the first, and so far only, fight to have a definitive conclusion. Tifa losing to Hitomi.
Perhaps the most divisive issue is the fact Monty took Artistic License with several characters, by endowing them with powers and abilities they don't possess in their respective canons - with Rinoa, Hitomi, the Kasumi X clones, and Kairi being the worst offenders.
Some fans are fine with it and simply chalk it up to Monty either invoking Rule of Cool, or feel he's trying to balance things out by making the presence of those characters feasible.
Purists, on the other hand, feel he's simply making those characters more powerful than they should be, to help them fight characters they'd otherwise stand no chance against. While other characters are being misrepresented.
Then there's the Fan Dumb who are okay with changes that help the characters they're rooting for, but go out of their way to point out why the opposition shouldn't be able to pull off the things that they do.