While I will say that anyone who watches the movie and the show will figure out who the main villain is within the first 20 minutes (or less), the movie was a fun movie to watch. The movie has a typical A and B story, with A being Bob, Linda and Teddy and B being the kids, and both end up meeting up for the climax of the film.
While Bob, Linda and Teddy have no real character outside of their main objective, the kids have their own things going on, besides the plot. Gene wants to have a concert at the Warf, Tina wants to make Jimmy Jr. her summer boyfriend, and Louise sees herself as a coward. Despite all these being setup, only Louise's story is actually plot relevant, where Gene's and Tina's resolve at the end and felt tacked on. I wasn't complaining, as I'm a Louise fan, so the movie felt like it rested on her shoulders. She really was the character who pushed the story forward, as Gene and Tina were in tow with her.
The music scores were cute, and most every character was dropped in the movie, and any that never made it in were dropped in the credits. Speaking of: the after credit scene was pointless and not worth sticking around for.
Without spoiling anything major, the movie was still fun to watch and I'd recommend it to a fan of the series. Don't go in expecting something fresh and ground breaking, as they took the safe route in story design. Just enjoy the movie for what it is.