So recently I just wrapped up both doing CT on my main original save and I just did a fresh playthrough of Shield intertwining both IoA and CT on an alt account. So with that in mind, especially doing IoA and CT on a fresh playthrough, let me post my thoughts...on BOTH! (Since I never talked about Isle of Armor really).
First things first, let's talk about the Wild Area concept, which is one of the big draws of the expansion pass. I love the concept of the Wild Area: frankly, the idea of a vast area to explore filled with Wild Pokemon is great! And a place where you can just explore, find Pokemon, and feel like you're exploring a new world is a really fun concept. But the original Wild Area just really disappoints on that front. First of all, there's a lack of diversity in biomes. There's really not much to explore here, and it's not really interesting: it's largely grassy fields and a few lakes/rivers and the Pokemon living here based on weather doesn't feel that natural. There's also no big secrets to find, no legendaries to find here, nothing really special. There was so much that could have been done with such a concept, but the original Wild Area...just doesn't deliver well enough on that front.
This is why the Wild Area concept is one of the biggest things I like about the Isle of Armor and Crown Tundra. They really take the concept of the Wild Area, and they do so much more with it. The Isle of Armor is an incredibly fun place to explore, with a wide diversity of habitats and biomes to explore: a beach, a forest, wetlands, a desert, caves, a mountainous area, a bunch of seas, and even some miniature islands to explore! There's a lot of biome diversity, and the lands are all interconnected so it doesn't feel linear at all. And the Pokemon distributed across them feel like Pokemon you would naturally see in each biome: Wooper, Goomy, and Croagunk in the wetlands, Venipede and Foongus in the forests, sea Pokemon in the islands, Sandile, Jangmo-o, and such in the desert, and vice versa, and it feels like one big island where a bunch of wild Pokemon are living in their natural habitats. It really feels like a place worth exploring. Crown Tundra takes it a step further, and you find snowy landscapes, more caves, a cold arctic sea, a cemetery, a big lake with a Tree in the middle, and some fields. But more importantly, the big draw of Crown Tundra: Legendary Pokemon, is done super nicely here. The exploration theme of Crown Tundra is done really well, and you find ancient ruins containing the Regis, a tree dedicated to the Galarian Birds, a shrine where Calyrex once lived, vice versa. It's what helps makes CT even more interesting and worth exploring. These areas really nail the Wild Area concept and are so much more interesting to explore than the original Wild Area.
Story-wise, the Isle of Armor and Crown Tundra have pretty nice campaigns. The Isle of Armor is kind of clunky and awkward to do if you do it on a post-game file, which is probably one of my few complaints with it, but when you intertwine it with the main game on a clear save, it's actually nice and a lot more interesting. I like the idea of a martial arts Dojo, where you sign up as a student and train to become stronger, which is the IoA's theme (growth), and it works well early in the journey alongside the main one: sign up for the Gym Challenge and do the gyms, all the while doing Mustard's trials along the way and exploring the IoA. Doing it was fun and added to the main game experience nicely in its own right. Avery was also a very interesting rival...he's a jerk rival who also has some pretty entertaining quirks (mainly his Psychic puns). Mustard is also a really fun and lovable guy who's also a really tough Trainer so I love him for that (Cheesed to meet you).
Kubfu isn't really a Pokemon that I cared about at first (other than that it's cute imho), but it's a fun Pokemon to get around early-mid game, and raising it was quite a nice journey. The game tries to sell you on the idea of you taking this timid little Kubfu and bonding with it, helping it grow into a confident Urshifu and going on a journey of discovery with it. This unfortunately lacks a lot of impact if you do it post-game, but in my recent playthrough I tried to use it on my main team alongside the rest, and this made the IoA experience even more fun in my eyes. Urshifu is fantastic in-game, throughout the fourth gym onwards I used the Single Strike form and its nigh unresisted STAB Coverage (and Wicked Blow guaranteeing crits) made it a force to be reckoned with. It's much cooler if you use Urshifu in an in-game playthrough and then wrap it off post-game with the final showdown with Mustard. Also getting to Gigantamax your starter is great to show it off against other G-Max Pokemon in gyms. It was...interesting seeing G-Max Inteleon literally snipe things from the high platform, especially Leon's Charizard.
Crown Tundra in and of itself is a really neat addition. As I said, I loved the idea of exploring and looking for Legendary Pokemon, and this is something that hasn't really been a thing since BW2. It was nice seeing the Regis being found in ancient ruins and needing puzzles (albeit somewhat simple ones) which made for a fun experience. The birds became roaming Pokemon, and this time they actually made the roaming concept interesting. Actually having to chase the birds in the overworld, and in each of the different wild areas, was a much more interesting concept than what we got before, and it's actually kind of fun to hunt these guys down. Calyrex also had a good story arc, and is a lot more likable than I had initially imagined it would be. It having a speaking role was a pleasant surprise, and taking possession of Peony's body to talk was pretty funny. I thoroughly enjoyed this segment. Peony himself is a lot more fun and likable in that he's clueless in all the best ways.
The Dynamax Adventures is a surprisingly fun side activity too. It's a neat and challenging adventure that is extremely fun and actually forces you to strategize and think with what you get from rentals, which makes it much, much more interesting than Max Raids. It's actually one of my favorite side activities in a Pokemon game besides Contests. The Galarian Star Tournament was pretty funny, and a good post-game "League Battle" format that involves Double Battles, which I always appreciate since Doubles is an underrepresented format. It's a good way to end off the story campaign and it's fun to do repeatedly simply for character banter between the SwSh characters, which is something I live for. Isle of Armor happens to have Restricted Sparring as a post-game option, and while I haven't done *too* much of it so far, I've enjoyed what little of it I played. Between all of this, this helps give Sword and Shield a thoroughly fun and engaging post-game, something the base game sorely lacked. And it brought back some new features like strong post-game bosses (Mustard, whole Galarian Star Tournament), some legendaries to look for (and some actual exploring to do, which hasn't been a thing in a looong time), and some fun battle facility formats (restricted sparring, Dynamax Adventures), stuff that hasn't been in Pokemon in a while. This is really the most fun I've had with Pokemon in a long, long time. Sword and Shield with the Expansion Pass added to it is just really fun, and I haven't actually enjoyed Pokemon to this extent since Gen 5, so I'm really happy with it. Gens 6-7 haven't really had something like this at all.
Overall, I really liked what the DLC brought to Sword and Shield. A lot of good things about both IoA and CT that they brought to the table, and doing it on a fresh playthrough it really feels like the experience I would get from a third version, all without having to buy a totally new game. The only main problem I have with the DLC is the approach of it: while old third versions are less consumer friendly, they tweaked things here and there in the base game's content. Like Emerald and Platinum would tweak the base locations and add some new things or change things up, or even add some new slice-of-life features. DLC doesn't really do this: it adds to the experience, which while brings it close to the third version experience, doesn't manage to totally replicate it. It also means the newly added/returning mons don't get acknowledged much in the main game. There were times where I thought "Man, wouldn't it be cool if Piers used Krookodile or Absol on his team?" or something like that. Even so, combined with the base experience of Sword and Shield, it really ups the experience of the game, and more than anything it really shows that Game Freak has still got it. I hope they can continue to implement some of these great ideas in future games like the potential DP remakes and Gen 9, because the Sword and Shield DLC is frankly a step in the right direction, and these ideas could definitely use some further refining in future games.