What will prevent this from ever becoming a good Witcher 3 clone is obvious throughout the demo - the writing is worthless. Plus, you have no real dialogue, just cutscenes.
Combat could be interesting on the highest difficulty levels, the dumb console game features can probably be turned off, such as the seeing through walls.
The bow made the impression of a built-in cheat. No crosshair trembling, damage output preview, no arrow arc, it shoots as if it were a rifle.
The non-choice between stealth vs combat approach must be some kind of ubisoft trademark. Dumbfucks, stealth is only interesting if you are in fear of having your ass kicked if you fail at it, i.e. if you are really vulnerable, so that there is a reward for stealth. Same dumb shit as Dishonored. Stealth means tough work - enemies who can hear, shadows that serve as cover, intelligent area design, not simply "walk on rooftops to be invisible". Your stealth sucks.
Interesting to see what else they will show, but I couldn't bear playing through this if I'll be annoyed by its shitty story and writing at every step,which will most probably be the case. Unless they demo something of the quality of the Red Baron quest, I'm unimpressed.
If they match Witcher 3's sex scenes with something more new-gen, like more bouncing boobies for example, which was a Witcher 3 weak side, that will be good, though I doubt it. They are probably going for the lowest possible PG rating.