After spending three evenings with the demo already, it's time to give a verdict, which feels a little bit like a preview for the game. There is actually a surprising amount of stuff to do in the demo and it will let you familiarize with the game very well.
Now, let's address the most important issue here right away: you can make Link battle in his underwear, but not Impa or Zelda? That's totally sexist, Nintendo! Bad game, 1/10.
But if you ignore this, the typical frame rate issues, which seems to be a general thing with everything Zelda now, as well questionable time travel story approach, it feels like a very good action game with a great sense of adventure, where you want to play more of it right away.
General
The demo is very well done. It lets you play the entire first chapter with two scenarios, but stops right when you're about to go to the four Champions, where you will have a free choice. You can still play some side missions / challenges at this point to get a feel for that and it even carries over your saved game to the full version of the game, where you can continue to play right away. That's very clever.
I personally really like the idea of the Central Hyrule Tower as your base from where you ascent or teleport to all the different missions. Together with the beautiful main theme of the game it all feels so much more adventurous and epic than Hyrule Warriors did.
The game essentially combines Legend Mode, Free Mode, Adventure Mode, and Bazaar from Hyrule Warriors all into one. You can play some side quests and challenges in between the main scenarios to enhance your characters, which is a nice change of pace. And you can replay the scenarios with any characters once your done with them, which can lead to some funny situations, where you're running into battle with Zelda and then unlock Link in the first mission.
Well, I've played the demo both in single-player and two-player mode, as well as in German and in English to get a feel for it all. Two-player mode is really sluggish. It's fun to play together, but having your field of view effectively halved is kind of annoying and the drops in the frame rate are really bad, especially if you attack one enemy together. It's a slow motion fest. But the first Hyrule Warriors had similar problems, so it's not all that surprising. And at least there is the option to play together at all, even if it's not ideal...
The single-player runs more smoothly for the most part and looks fine, but it's still noticeable that the frame rate isn't the best. It seems to be around 30FPS with occasional drops to 20. And if you're used to having at least 60FPS, it can be quite the headache.
At least the sound is mostly great, though the voice acting in German for Impa is super annoying. The way she says "Hallo" (Hello) whenever you switch to her feels over-the-top and was unnerving me after a while. Her English voice actress on the other hand is very subtle, almost like the opposite. The English cast is sometimes a little bit hard to understand, though. And overall it's simply strange to hear all the characters, except Link of course, talk during the battle. But it's not necessarily bad and only adds to the presentation, where it's even nice that they've extended the voice acting cast for this game.
The options are quite extensive and allow you to invert camera controls (you really need to mention this by now, it's not a given with Nintendo games any longer). You can't change between different button layouts like in Hyrule Warriors, however, probably because using Y to attack and B to spring matches Breath of the Wild already, so there was no need for separate "Zelda" controls. It might need some adjusting if you're used to those.
Battlefields
Going into the "Battle of Hyrule Field" did feel like a culture shock at first, after the freedom that Breath of the Wild has provided. Of course I didn't expect to be able to climb walls and using walls to surround the battlefield is certainly fine. But at certain points you're basically running against an invisible wall...
Yes, Breath of the Wild did this as well at the borders of its map in the desert and ocean, but here it feels so much more artificial. And when Link can't even get past two feet high rocks anymore it just looks ridiculous. You can't even jump down from one of these wooden enemy camps, where instead you have its platforms surrounded by invisible walls again that you even can wall jump from... Really weird.
Problem is that there is a mess, where you often can't tell which elements on the map can be interacted with and which ones simply act as a barrier. There is a lot of needless clutter on the battlefields, which even makes finding the hidden Koroks more difficult than it's probably supposed to be (more about the Koroks in a separate post). I never had such issues with Breath of the Wild and while Age of Calamity borrows a lot from its source material, it all feels closer to Hyrule Warriors in the overall quality, much closer than I originally expected.
It's still great to see places like Mabe Village or the Lon Lon Ranch before their destruction. All the towns and villages around Hyrule Field really make you wonder how Breath of the Wild would have been with less ruins and more population.
It will also be interesting to compare the maps with the original, but "Breach of Demise" almost feels like a completely different area. I can recognize parts of it, but the whole rock formations seem much larger than in the original. I could be wrong here and the overall map matches the one from Breath of the Wild. And it's nice to finally see the "Royal Ancient Lab" in full glory, even though this only happens during the cutscenes.
Oh, and you can find Blupees. Though, I wasn't able to catch one yet.
Characters and Combat
As for the playable cast, I think are well done and quite enjoyable for the most part. Zelda is probably the one that I've enjoyed the least so far, but that's mainly because you can't cut grass with your main attacks. It makes sense, but it doesn't feel good and you're missing out on materials with her. She looks gorgeous, though, and I like that they are able to do something different with her here, where she can feel useful.
Impa is a lot of fun, once you've figured her out with the seals. She's by far the most powerful character of the three with her ability to create multiple clones. She's literally an army of one and can quickly cause a ton of damage.
Link is the most basic one, but still fun to play. He's the "cut all the grass and all the trees" character for me, where I just can't stop destroying the environment as him. Using the bow and shield surfing is also a lot of fun, where it's a shame that the two ladies don't seem to have a move that lets you go faster. But it's fun to experiment with what the characters can do in any given situation, especially now since everyone can also go and fight in the air with their gliders.
You can also get a Lizalfos Boomerang for Link, which plays like any of the one-handed weapons, but with a twist. Instead of the normal Spin Attack you do throw it around, which is pretty cool. It's nice that weapons of the same weapon type can still have some smaller differences, which will probably be true for the Master Sword as well.
It's also incredible that every character gets to use the four Sheikah Slate Runes differently. Those are very easy to access and quite creative, where this is a huge upgrade from the item system in Hyrule Warriors. It already starts with how quickly you are able to use them: hold the respective shoulder button and then press A, B, X or Y. It doesn't get any quicker than that and it feels great.
The Runes are accessed with the R button, while three different elemental rods and food are used in the same way with the L button. The L items need to be replenished and work the same for everyone, however.
Last but not least, you need to mention the stronger monsters, where in case of the demo it's mostly Moblins, some Wizzrobes and a single Guardian. The latter gets even treated like a boss and has a whole scenario about avoiding and destroying just it...
One of my complaints about the first Hyrule Warriors was that certain foes like the Darknuts or Moblins felt like a joke when compared to their counterparts from the Zelda series. This was especially the case with the Darknuts, who are the mightiest enemies in Twilight Princess, but a complete pushover in Hyrule Warriors.
Well, they didn't make the same mistake twice, where they even went a little overboard here. The stronger foes now actually feel more much stronger than they've used to be in Breath of the Wild. You can easily take out a Guardian early on, if you know how. And red Moblins aren't usually that much of a threat, while Wizzrobes can be easily one-shotted. In Age of Calamity all of these enemies feel a lot more dangerous now, but this only going to make things more interesting.
Conclusion
As said in the beginning, this is a demo done right. Even though it limits you to a couple of missions, it's hard to put it down and it really makes you want to continue in the full game right away. There are some deficits on the technical side, however, where it's still a Warriors game underneath, with all its glory and issues.