This is actually the game Bethesda should have been making. Everyone who mods Skyrim (myself included) to be grimdark or gritty or extra bloody really should play this game because it's essentially what I'm after. The writing's consistently interesting and good, the gameplay has major improvements over Skyrim/Fallout, and the atmosphere is amazingly immersive, especially for Celtic myth fans like me.
For the nitty gritty people who really want to know how this game has improved over Skyrim:
Health does not regenerate naturally. This is a feature of Oblivion that a lot of us were sad to see go in Skyrim. You have easy access to healing items and spells, and can still do the old "I eat all the cheese" if something brings your HP low.
Mana does regenerate naturally, and you still have items to replenish it.
Stamina does regen, but it's been changed to help the flow of combat. In Skyrim, your stamina is mostly used to spam power attacks, shield bashing, or if you're late game, to spam knocking them over with the shield rush perk, because the only way to dodge attacks is by spacing the enemy's animations. It regens pretty slow and if you're a mage you pretty much ignore it. I'm simplifying, but that's the main things people use it for. In this game, light and heavy attacks consume stamina and it replenishes Dark Souls style; you use it up, and it comes back after a short delay.
They added a dodge. It works amazing, and to start with you have 3 charges. It consumes stamina just like your attacks.
All the combat is in first person. The animations flow great, and each weapon has a different identity (about the same as in Skyrim -- I haven't gotten too far yet). Some people might not like that, but the animations are at least on a Vermintide 2 level. The only complaint I have is that weapon ranges don't seem right -- as in, I'll have a longsword but have to be physically touching the enemy to hit them.
For leveling up and perks, you have a new set of attributes (not just health/stam/magicka -- think DnD stats with different names). The devs have done us a major favor and shown us everything that the level ups increase, so there's no need to explain them.
Perk trees are back, and though not as flashy as Skyrim's screen, they are way more powerful. You can specialize your builds or do whatever you want, and most importantly read what every perk does very easily.
The only thing I have a gripe with is the crafting, which I think they took notes on from ESO or other MMOs. Essentially, you can improve your chances of crafting a better item by increasing the amount of materials you use to craft the item -- guarantee you make a high quality sword by shoving more ore into it, I guess, but that's how it works. It takes me out of the game a little, and the enemies respawn to help you farm materials (I have yet to find a lore reason for enemies respawning so much after I routinely commit stag and wolf genocide in the first area). However, the devs have already implemented crafting from storage, so that makes it a lot easier.
If you care about visual fidelity a lot, you might be annoyed with the quality and some random issues (like pixellated faces or pixellated clouds in the distance), but it all works fine together. Some of the magic FX could use work, but they give strong Oblivion vibes and I like that. There's nothing wrong with visual consistency even when it's not in hyper-realistic 4k textures for everything. Not every game needs 100gb of textures, and this is one of them that really doesn't. The devs have made a lot of neat spectacles and I'm too focused on playing to care about how it looks.
The most major issue I've found is that the crafting station for "handcrafting" (smithing) is labelled "grindstone" and is not, in fact, a grindstone. It is a workbench with tools on it. In Skyrim, you used a grindstone to increase the strength of your weapon. In this game, the grindstone (which is located across from the aforementioned workbench) remains alone, useless, and depressed, just like me after realizing how much time I spent writing this review.