I've played a little bit with the demo… this is quite a polished game. Very positive overall.
There's a learning curve and some of the descriptions are not always clear to me yet, because I haven't had many combats or used many skills. But in general, everything is described and detailed in helpful tooltips, and at the beginning there are mini-tutorials presenting the items and the panels. All of that can be found back in the Codex any time.
Visuals were on ultra when I started, which made the GPU somewhat warm but nothing excessive. I turned it down a few notches because I prefer quiet to gorgeous graphics (I may turn it back up now and then). It remains very pretty on medium/high, so it shouldn't be a problem for older cards hopefully.
The music is splendid and the sounds immersive. Voice acting is very good too, and very natural. It's funny to hear the military jargon of the Roman army, I should have brushed up on that.
And I've met or heard about characters I knew from translations made long ago at school, which feels a little strange. When you walk by, you often hear the comments of people on what happened, or on other ongoing matters. Everything is subtitled, audio is English or German, and there are many other languages selections for the texts (and the UI I suppose).
On the minus side, there's little interaction with the environment or the NPCs, it's very functional but doesn't go beyond the scope of the quest. It's not necessarily bad, but it feels like a lost opportunity when there are so many other elements that make it a believable world. So it's more comparable to a tactical game like Solasta (but several levels beyond of course) than a D:OS2.
Combat seems very engaging, it requires a good coordination between the party members. It looks like fights are easily lost on small mistakes.
I've only encountered a few minor bugs related to the control so far, it seems quite stable. I can't judge yet if there are any problems of stats, skills and so on.