THIS REVIEW IS MEANT TO BE READ AFTER YOU'VE SEEN THE EPISODE. I WON'T BE GIVING A PLOT SYNOPSIS FOR THE EPISODE AND I WILL BE REFERENCING SPECIFIC EVENTS, SO IF YOU HAVEN'T SEEN THE EPISODE THEN THIS WON'T MAKE MUCH SENSE.
Going off of Headhunters you'd think that Gravity Falls would wait a few more episodes before adding anything new to its formula. It has a good set up, it can basically just insert a new monster into every episode and let the jokes write themselves, overall it could follow the traditional kid's cartoon formula and be comfortable, but instead it does one of the things that makes Gravity Falls such a great show. It adds another important element of the story, the main villain of season one, into the mix without giving the audience time to become comfortable with the show's direction, an act that keeps them on their toes that the show will repeat a few more times in the future. This villain is what drives The Hand That Rocks the Mabel and he's a big reason why it's a fantastic episode.
Gideon Gleeful is a creepy little monster, which makes him a perfect villain to compliment the main cast of heroes in Gravity Falls. If there's one thing that defines Dipper and Mabel's pursuit of the supernatural other than its constant danger is that it's always a very pure one. They rarely try to exploit the supernatural beings they find for their own gain without thinking it through first, and if they do they (usually) learn their lesson from the inevitable bad things that transpire because of their greed and selfishness. Gideon is the exact opposite. He views the world around him and the people and beings in it as things for him to use, more as objects and obstacles than as the living souls they are. This means that when he becomes interested in Mabel he views romancing her less as something involving her and more as a thing that she allows him to obtain. It's not a shared experience between the two of them, it's a thing she has that he wants to get and as someone who's used to getting what he wants he doesn't take her rejection well. The ways he pressures Mabel into continuing to go out with him all seem big and ridiculous, but all reflect ways that actual people pressure others into unhealthy relationships and by making them so big the writers allow their show to teach kids an important message that's surprisingly rare in cartoons, that of it being okay and healthy to say no. Love is such a given in most kids shows and movies that it seems like a no-brainer, that if you just act like yourself the people who present themselves to you will be perfect fits for you, but as anyone who's ever dated anyone before knows that's not the case and it's refreshing to see a show like Gravity Falls representing such an important and rare message to kids, especially considering it's a Disney show, the biggest modern pusher of the "True Love at First Sight" bullshit that tons of generations have grown up on. That description makes this episode and the show in general sound rather cynical, but in reality it's just surprisingly realistic. Mabel does find romantic success in the future and there are plenty of other messages that are much more hopeful, but The Hand That Rocks the Mabel benefits from it's less happy one, making it one of the episode's biggest strengths.
But the way the show conveys this is through Gideon, who is without a doubt a great villain. He's a disgusting little slime ball, but he's also very dynamic which allows the writers to do a lot with him. One minute he's manipulating a crowd of people, the next he's smashing things using his psychic powers. He can do so many things that his versatility is in itself threatening. Thurop Van Orman (look up his picture and you'll get a laugh) absolutely knocks it out of the park as Gideon. Every time he's speaking you can tell he's having a blast in the role and he channels that energy and joy into every word, making Gideon one of the best performed characters in a cast that pretty much never disappoints. His ability to switch from funny to threatening on a dime means that's he's much more unpredictable than most other villains on Gravity Falls, who usually fall into either the "trickster" or "loud and smashy" category. The show defiantly takes full advantage of him in the future, using the character to his full worth.
Mabel also finally gets to shine in this episode. It's a point of argument among the fan base whether Gravity Falls is a show about a duo or if Dipper is the protagonist and Mabel the deuteragonist, but this is the first real Mabel episode of the show. While Dipper gets more episodes over the course of the show as the focus it's always refreshing to see Mabel get the spotlight as it allows her to show emotions other than her normal happy-go-lucky optimism. Seeing her scared and stressed about something other than a giant monster trying to kill her and her brother is different than the norm and her conversation with Wendy about breaking up with guys is surprisingly heartwarming considering it's really just a giant joke that happens to further the plot. It's just enjoyable to see Mabel break from her usual character traits, just like it is with all the other characters on the show.
If there's one criticism that could be directed at this episode it's that it's not as funny as it could have been. Don't get me wrong, it's really funny, but there aren't really any standout jokes like there are in some other episodes that really hang with you after the credits roll, like "so... we're gnomes, get that one out of the way" from Tourist Trapped or "avenge me kids! AVENGE ME!" from Headhunters. It's not a huge drawback, as the character work in this episode makes up for any small lack of humor in spades, but it feels like there's some missed potential room for funnier jokes.
The last thing that I want to mention is what I feel is possibly the best moment of the entire first season of Gravity Falls is in this episode. The Hand That Rocks the Mabel was the first episode of Gravity Falls I ever saw. I watched about two minutes of the beginning before switching the channel when it first aired back in 2012 and I'm so glad I did, because without having gotten connected to the character I would have missed out on one of the best reveals ever. Gravity Falls is great at dramatically revealing new information, but the ending showing Gideon posses journal number two is perfect. It sets him up as a continuing threat, show's how far he's willing to go to have Mabel, and reveals the existence of another journal. It's short, but it's oh so sweet and simply incredible.
Overall The Hand that Rocks the Mabel is a great episode. It misses a few possible jokes, which is a little frustrating, but in the end it's a fantastic episode showing a rare message through the lens of a character that we can never get enough of.
-The score for this show is great. I don't know how I haven't mentioned that yet but the score is literally never anything but perfect
-Once again this show shines in it's little details that make the world feel more complete. The people at the Mystery Shack and in the Tent of Telepathy are in other places around town in later episodes and on the lake in The Legend of the Gobblewonker. It might just be to save on character designs, but it makes the world feel much more real and alive.