Approximately 10 months after the release of Pokémon Scarlet and Pokémon Violet, the first DLC in "The Hidden Treasure of Area Zero" post-game content has been released. I myself had been optimistic, yet cautious, for the release of The Teal Mask DLC, as I had not been particularly happy with the post-game content presented thus far.
Before I continue, I'd like to give this form of recommendation: If you are already currently playing the games and plan to buy the DLC, feel free to journey into Kitakami. If not, then you may feel better waiting until the full release of the planned post-game DLC content. As we go into my thoughts, I will be discussing spoilers for the DLC and will be speaking assuming you have played the base game as well. Keep that in mind going forward.
The Pokémon S/V: The Teal Mask DLC takes your player character on a field trip from the land of Paldea to the region of Kitakami, a small wooded region to the south of Pokémon Diamond and Pokémon Pearl's Sinnoh region. As a collector, I find that my first thought goes to the region's Pokédex, which is comprised of Pokémon already present in the 9th generation of Pokémon games, as well as a gathering of new entries. In total, 200 Pokémon can be found in the land of Kitakami; this can be compared to the Isle of Armor or Crown Tundra Pokédex totals of 210, both of which were DLC regions for the Pokémon Sword and Pokémon Shield games. This, however, can be set aside numerally; A handful of Pokémon were added over time with the Unrivaled 7-star Tera Raids, as well as the Pokémon Home connectivity update.
As far as new entries to the world of Pokémon go, we received 7 new Pokémon and 1 new form for a pre-existing Pokémon. Poltchageist and Sinischa are a Kitakami-native convergence of the Sinistea line, while Dipplin is a new evolution for Applin by means of an apple found in the Kitakami region. Joining the ever-growing pile of Legendary Pokémon are the "Loyal Three" -- or as those who play through the story might deem, "Disloyal Three" -- Monkidori, Okidogi, and Fezandipiti. The titular Teal Mask belongs to the incredibly cute Ogerpon, who comes with 3 other masks as well for a fun ability that changes types and powers. Altogether, these additions are very charming in both design and utility (supposedly Ogerpon will be a solution for current VGC headaches such as Urshifu).
— "Do you think I can put this on my resume?"
Moving on from the collecting side of things, I want to move on to the overall gameplay improvements presented in the DLC. Quality of life changes such as improved performance in the PC boxes and new camera features were vastly welcomed as well as fiercely demanded; for the aforementioned 10 months, the PC boxes would take several seconds to load icons of stored Pokémon properly, which was a huge downgrade compared to previous titles and caused many headaches for those who frequented their boxes.
New additions with the DLC include the Ogre Oustin' minigame, where you collect berries to turn into base stat-increasing mochi, and also include-- Well... That's it, really. A second 6-star raid can be found in the region in addition to your daily one in Paldea, but other than Ogre Oustin', there are no new gameplay additions. I, personally, was hoping for some form of post-game battle challenge, where I could use the Pokémon I've trained in interesting manners that aren't online PvP or the co-operative (yet PvP by nature of co-operation) Tera Raids. I expect, going off of the previous generation's DLC, that what I'm hoping for will be added in the next set of DLC. At the very least, the Ogre Oustin' minigame adds the "Fresh-Start Mochi", a usable and farmable item that can reset your Pokemon's base stat totals.
— "Just the way that people like to see things that cost a lot of money on to be remade: exactly the same as before!"
Moving to the story, if you played through the base story of Scarlet and Violet, then you're aware that the character writing for this generation is phenomenal. The Teal Mask adds more of what you were familiar with through the base story, but with a new cast specific to the DLC. The two characters of note during this story are Carmine and Kieran, two siblings who are native to the Kitakami region and attend Blueberry Academy, the academy that is not only set to be the setting of the second DLC but is also stated to be in the Unova region (please... please learn from Brilliant Diamond and Shining Pearl when you inevitably and most likely prematurely make the Gen 5 remakes, Game Freak...). Both siblings have the opposite spectrum of rough exteriors: Carmine is stand-offish and combatitive, while Kieran is shy and reserved to an extreme. Despite this, both characters have good hearts and are charming overall.
The main story acts as a retelling of the tale of Momotaro, a popular story from Japanese folklore that tells of the titular hero banding up with a talking dog, monkey, and pheasant in order to fight a band of ogres. The Teal Mask looks at this from a different angle; what if Momotaro (who is not represented in the DLC yet but is supposedly hinted to be a future DLC addition) and his crew were not heroes, but villains who attacked an innocent ogre. The main characters move to clear the ogre's name that has been besmirched by this event for generations, as well as retrieve the treasures the "Loyal Three" stole -- bringing back the theme of treasures from the main game in the form of masks that Ogerpon kept, treasuring the memories of her deceased (and murdered!) friend.
— "I would die for Kieran and Carmine to be happy."
The post-game of the DLC, although I believe this can be undergone at any point that the player reaches 150 Pokémon caught in the Kitakami dex, entails the player working with Perrin, the descendant of Adaman from Pokémon Legends: Arceus (although this is not mentioned in-game, it's immediately obvious from her design and backstory). Together, you set out to find the Bloodmoon Beast, a special Ursaluna that supposedly traveled to the land of Kitakami from Hisui both in time and location; Hisui being the ancient name for the land of Sinnoh, north of Kitakami across the sea. Altogether, the search for this Ursaluna is very remniscient of Pokémon Legends: Arceus, as you have to sneak up on Pokémon and "capture" them (using a camera) while music from Legends plays. During your fight against the Bloodmoon Ursaluna (which at the moment is a special one-time capture with no other known way of obtaining), the Alpha Fight theme from Legends plays. I had fun with this entire segment, but later that week I ended up having the thought: was it fun because I was reminded of a different game...?
Ultimately, while I did enjoy the approximately 6-8 hours that it took me to complete the DLC, I feel that I would have felt disappointed if I had come back after a 10 month wait. Those looking specifically for story and character beats will be pleased; those looking for gameplay enhancements and added longevity will have to wait for the second half of the $35USD DLC pack, slated to release in Winter 2023. I feel as though my overall recommendation could potentially be changed to "Don't buy a Pokémon game until the physical cartridge that includes the DLC pack is released", if you wanted to be extreme about the current situation. Ultimately, however, Pokémon is a community based game and with that comes some sense of FOMO -- Sometimes you're going to buy a game that isn't perfect so you can play it with your friends. That's okay, too.
Oh, this was also really cool to see in a Pokémon game.
— "Technology is incredible!"