So it seems much of the character focus in this special is on Zipp, not just on her trying to figure out why magic has become rather faulty recently, but also dealing with pressure from her mother to return to Zephyr Heights for royal duties. Even so, the other main ponies have their own moments of interest, such as Hitch secretly caring for a large egg he found on the beach, Sunny struggling to understand her new alicorn magic that she's currently unable to control when and where it activates, and Pipp and Izzy prepare a surprise gift for Sunny by repairing the lantern her dad had made for her (proving that at least some objects from Sunny's old home really were damaged when that place was destroyed). In addition, everyone is preparing for the upcoming Maretime Bay Day festival (so I guess that's where the video game tie-in comes from, though whatever the content of that game will be is obviously not going to be canon to the main series).
Additionally, there's still lingering tensions between the three tribes, especially by the earth ponies who express displeasure over apparently being the only ones still without magic (even Hitch admits to feeling jealous over not having magic, but at least he's respectful enough to not let it cloud his judgement, unlike most of the other earth ponies), the most vocal of whom is unquestionably Poesy Bloom (whose character design is based on the G1 pony who inspired G4's Fluttershy, which admittedly makes her rather nasty attitude in this special quite jarring).
I wasn't exactly pleased to see Zipp be so evasive around her friends and thinking she could solve the mystery of faulty magic on her own. To me, it just seemed like a pointless waste of time for much of the first half of the special. (I guess this means one reason I like the Tell Your Tale series is because the short runtime practically forces it to not beat around the bush too much and just get straight to the point.) Though I did like the little detail that Zipp's phone is one of those foldable smartphones. (I'd also like to note that in one moment of glitching magic, Windy points out that she's usually a pretty good flyer, indicating that this special takes place after at least the first few episodes of Tell Your Tale.)
Thankfully, all of the Main Five are able to figure out prior to the festival that hatred and distrust among the ponies has been what's causing magic to glitch out, and they make a good effort to use the festival to promote unity among all ponies, but jealousy and hatred among the earth ponies proves so great that it unleashes a powerful storm and opens a bottomless void in the ground. This time, the complete loss of magic not only prevents pegasi from flying and unicorns from casting spells, but also causes the hooves of earth ponies to get stuck to the ground.
The disaster is averted when everyone realizes that working together to help each other is able to undo those consequences (Sunny even used her repaired lantern and alicorn magic to rescue Poesy from the void), and with true unity fully restored, magic returns even stronger than before, enough to give even the earth ponies magic such as making plants grow rapidly (and allowing Hitch to communicate directly with animals). For those of you who have always wondered about whether earth ponies even have any magic at all, it seems now you have a very definitive answer.
After all of that happened, the egg Hitch found on the beach hatches into a dragon, which Sunny notes have not been seen by any ponies for "generations", so at least that provides a somewhat minimal amount of time that has passed since the events of G4. It also leaves us wondering how much the dragons might have changed throughout that period of time. Also, Queen Haven visited the festival, and after a conversation with Zipp, she eventually allows Zipp to stay in Maretime Bay with her friends. Zipp even ends up earning the title of "Detective" for her efforts.
In addition, near the end of the special, we also got a brief foreshadowing of potentially the first real villain of the series, who claims that now that the ponies have regained full control over their magic, she can finally "take back what is rightfully mine", so we may yet learn more about why all magic was lost in the first place, such as where those magical Unity Crystals came from and why they were separated. (From what little we could see of her in the shadows, I would best describe her as a unicorn that sort of resembles Nightmare Moon.)
As for the animation, while the quality is certainly not as great as the movie, I will say that, for what will after all be a multi-episode series, it's actually rather standard at worst, so I'll consider it as "good enough" (it could be better, but it could also be much worse, and there's always the possibility for improvement as the series goes on).
Overall, this seemed like a rather decent way to start off the series, almost like those two-part episodes that started almost every season of FiM, and I'll be looking forward to the full-length episodes when they come out in September, four months from now.