Oh and also apart from the great performance and nicely implemented UI. Oh and finally good/decent player physics. Apart from the nice animations and weapon effects it really is a downgrade.
What? The game does not perform well given its fairly mediocre presentation. There's some nice texture work but that's about it. The UI is improved over the Gothic games but I liked Risen's UI better. Physics were pretty wonky, as my character would often get stuck on collision and then suddenly slide 10 feet away.
Other notable downgrades:
1) Combat is fairly mindless. Roll in, pull off a three hit combo, then roll away when enemies charge up to perform their slow and extremely obvious power attacks. In Gothic 1&2, fights were far more engaging. You had to perfectly time your attacks, blocks and dodges. In Arcania, you just roll around all the time. As mentioned in an earlier post, it feels more like Divinity 2 than Gothic.
2) NPCs don't seem to care about you invading their house and stealing their stuff.
3) Invisible walls everywhere. Why can't I wade into a shallow pool of water?
4) You can see perfectly fine at night. Night-time was serious business in the Gothic games because you couldn't see anything, requiring you to carry a torch. Even then, it was risky to travel at night because the torch only had a limited light radius and you never knew what you might run into.
5) You can instantly eat food and use potions while moving. This undermines the intensity of combat. In Gothic, you had to stop and slowly drink potions or eat food, which meant it wasn't a viable option during combat. Here you just drink potions while rolling around.
6) Way too easy. In Gothic 1&2, your first encounters with Goblins or Mole Rats usually ended in death. You had to learn their attack patterns before you stood a chance. in Arcania, just mash the attack button and then roll away before enemies do their power attacks.
So yeah, based on the demo, I think Arcania definitely feels like a downgrade from Gothic. Note that the issues all pertain to fundamental parts of the game which will remain the same in the full version.
Risen is a far worthier successor to Gothic.