It did make changes but overall I think the majority of them worked for an adaptation since they either didn't change anything major about the story/original intent or the change still kept the original intent intact. In the case of introducing Motorball when/how they did, this was a scene that doesn't exist in the manga BUT does a good job of introducing an element early that will play a big part later, in other words, it worked for an adaptation. The way she gains the Damascus blade for example doesn't really remove anything major but does still give it importance to her with it being taken from Zapan.
There are couple exceptions to this where I'm either undecided or didn't like the change.
- Having her sign up and play Motorball 'professionally' when she did totally changed the original motivation behind it, essentially removing a character arc.
- Victors motivation and how much of a villainous role I'm undecided on, though it did give the first movie (which would be 3 books) a consistent antagonist whereas the manga didn't have one up until Dr.Nova.
- The way she obtained the Berserker armour and the exposition given on it I think both gave too much information on Alita's backstory and made it too obvious to what Alita's backstory is too way too soon.
Oh, and Alita is named after Ido's dead cat, not his non existent wife and daughter...Not a huge change, it probably works better for an adaption so it sounds less silly, but I wish they kept it anyway.