The Judas Contract is based off of the 1984 comic of the same name.
Now you may be wondering if the film will be more like the comic or like the show and the answer is surprisingly both.
The basic story is done more faithful to the comic but there's a lot of clever stuff from the show that was included in the film. The beginning has a group of mentioned villains that the Titans first fought called "The Fearsome Five" which I think is a clever referance to the HIVE Five since the HIVE in the movie are cultist and are very different from the series.
Before I get into spoilers my general thoughts on the film is that it was great. 8/10 IMO.
Spoilers! I won't talk spoilers in too much detail in case you want to see the film without reading in depth spoilers.
The film's portrayale of Terra really surprised me. It's like they combined the comic and show Terra together. Sometimes she about to go all crazy on someone (like Azula from Avatar) other times you will feel very sorry for her and she can sometimes get sympathetic (especially to Beast Boy later on).
Terra has a different origin story than in the comics.
The Slade and Terra thing is in the film but it's actually pretty different than the comics surprisingly.
Brother Blood is similar in his over the top personality but he's like a evil preacher in this which was interesting.
Blue Beetle has a side story that while wasn't necessary was neat to see how his family (especially his father) view his condition. Plus he meets a girl that he starts to grow feelings for who comic fans may recognize.
Blood's final form reminded of the Master of Games powers.
The last two scenes was really well set up potential sequels. The Titans get a new member (I won't say who but it's not Jericho like in the comic). Jericho is in the film but his character is like a combination of Jericho and Grant Wilson so that was interesting.