Dark Phoenix was not THAT bad. I actually really enjoyed it. Certainly better than Apocalpse, X3, and X-Men Origins.
I get that it's not the "proper" storyline from the comics and that timelines are an issue, but I found it entertaining and still love the characters.
The main problem was that it wasn't an "epic" blockbuster-type film, which is what the story demands. But considering the development hell of going from 2 films to 1, I can forgive it.
I like that they actually gave an Xman (Jean Grey) other than Professor X/Wolverine/Magneto some time to shine. And ending the series on a "protect your family" theme was a good message to end it.
Yeah, it has a lot of little faults like some dialogue and underemphasizing Cyclops and Quicksilver, but I liked that is gave us a message of hope and family.