This movie fell flat for me. I love both Teen Titans and TTG, but quite unlike the previous year's endeavor, Teen Titans Go! to the Movies, none of it was particularly engaging.
Perhaps it was the direction, or simply the fact the the actors had to each portray two different versions of their respective characters, but the actors just did not seem as committed to either version as they had when performing these roles in each TV series.
The humor was okay at best. The plot, even with its "twist" of an ending, was mostly predictable. A shame, as the years-long controversy over which is the "better" version of Teen Titans left plenty of room for humorous exploration and hi-jinks. Instead, the controversy was used as a lame excuse to push fourth wall jokes as opposed to introducing some clever nods to the viewing audience.
Overall, not a bad movie. I usually do not pan "not a bad" movies, but this one just didn't provide enough for a "like".