It's not so much that it's bad as it's not good. The script is very generic. Why does Akiva Goldsman keep getting hired to write screenplays? He must know where all the bodies are buried in Hollywood. It's like he has a computer at home where he enters in a few keywords and a minute later the computer spits out a full script.
The actress was fine as Starfire--although, I'd've preferred they gave an Asian actress the part, as there aren't many opportunities in the Titans for Asian actors--but why was she stuck in a 1970s Blaxploitation movie, right down to the music and the clothing? And the way she gets her Earth name, Kory Anders, seems to preclude her ever being Koriand'r unless by some fantastic coincidence. It appears they opted for her to have pyrotechnic powers because that was more affordable in the effects budget.
But the Starfire part of the story was a little more entertaining than all the stuff surrounding Raven.
Akiva Goldsman can be confident that his record for schlock remains unbroken. Give this man a slow clap.