I really liked it, even more than the previous two.
Crazy Wild-West setting on Mars + more surreal cyborg freaks
This one also has that Tsukushi style children suffering, which is fun
I think Gunm is like GiTS in that the side characters are often more fun than the main, 80's action girl, character. And in this one Alita is just a potato too
Didn't really care that much about learning about the prequel backstory, though it was interesting. I just enjoyed the ride of the series-long flashback