In case you're not familiar with the events of the previous films in the Step Up series, here's a quick recap:
In Step Up, Nora (Jenna Dewan) is a student at the Maryland School of the Arts (MSA) whose senior dance project is in jeopardy when her dance partner suffers an injury. Fortunately, the school's streetwise janitor Tyler (Channing Tatum) was there to help. It's kind of like Good Will Hunting meets Flashdance, except there's not nearly as much dancing as you'd expect or hope.
In Step Up 2: The Streets, Tyler briefly returns to convince his friend Andie (Briana Evigan) to attend the MSA. Andie had been a part of a street dancing crew, but they turned their back on her when school activities started to take a lot of her time. So she put together her own crew comprised of several other school outcasts, including Moose (Adam Sevani), in hopes of showing what they can do in a neighborhood competition known as "The Streets". It's The Bad News Bears but with dancing.
In Step Up 3D, Moose has graduated from the MSA and has started college in New York City with best friend Camille (Alyson Stoner, who also had a small part in the first movie). He's all set to be a serious engineering student until he's distracted by a guy with nice shoes and eventually ends up in another dance crew. Most of the crew are in a really nice apartment, but they've spent all their money lining the walls with boom boxes and shoes. Unless they can win a dance competition, they'll be evicted for not paying the rent. It's Breakin' 2: Electrict Boogaloo but with hip-hop instead of breakdancing.
In the latest installment, the action moves down to Miami where a group of kids are trying to win a contest. The first YouTube channel to get at least ten million hits will win a $100,000 prize, and they're trying to do it with flash mobs. They have no problem with stopping traffic on a busy street or crashing an art exhibition or a fancy dinner, so they make enemies of the public and the law, but they're in good shape to win the competition. But it could be all for naught if a big real estate developer gets his way and tears down most of their neighborhood in order to build a new luxury hotel resort. It's this "band of misfits versus greedy corporate takeover" story that makes Step Up Revolution the Ernest Goes to Camp of dance movies.
In most ways, Step Up Revolution is actually a big step down from parts 2 and 3. Aside from the final dance number, which has a much more epic scale than anything else we've seen in the series, there's much less actual dancing in the fourth installment than the second or third, and what we do get usually comes in the form of a flash mob scene that is both short-lived and weirdly-edited. Like the first and second parts of the series, there are also more "classy" dance sequences in connection to a formal dance troupe, but no one really goes to a Step Up movie to see those.
As with its predecessor, Step Up Revolution is in 3D, and that is unfortunately the way that I saw it. The film didn't really benefit from 3D at all, and in several areas it was significantly hurt by it. A lot of scenes involving fast motion (like much of the dancing) appeared very stuttery, and on the few occasions in which there was a rapid change in the depth of something presented on screen, I found it hard to keep it in focus. That's probably because a lot of the film was shot with much too shallow focus for a 3D movie so that backgrounds were often blurry. I didn't like the film's excessive use of backlighting, and some scenes (like the entire opening sequence) came off looking almost cartoonish so that they appeared more animated than live-action, much as if they were ripped from a Miami-based Grand Theft Auto: Vice City video game.
As if I needed any other reasons to dislike the movie, Step Up Revolution has one of the lamest endings in recent memory. It involves a couple of cameos from the previous films, but they're just thrown in without any explanation as to what kind of connection they have to the characters of this movie. And of the two big issues resolved by the conclusion, one was a cop out completely lacking in believability, and the other was actively hypocritical and almost the exact opposite of the message they were trying to send mere seconds earlier.
If you see any of the movies in the series, then it's almost certainly for the dancing rather than the plot. Although Step Up Revolution doesn't have as much dancing as I'd hoped to see, the final sequence is legitimately impressive, and some of the other flash mob scenes also have good stuff even if they tend to be too short and questionable camerawork. If you really need a dance fix, and if you're willing to overlook the huge selection of better options on DVD, then Step Up Revolution (preferably in 2D) may do in a pinch.