There are a few factors that help maintain realistic expectations:
First, expect games of a generation to have similar graphical capability, because CDPR do not have access to 'development magic' not possessed by other developers.
Consequently, I would expect TW3 to have similar graphical capability to other current gen games I have played:
- Assassin's Creed Unity
- Shadow of Mordor
- Tomb Raider (Definitive Edition)
- Dragon Age Inquisition
Of those, I think it will look closest to Dragon Age, from the gameplay videos I have seen.
Expecting some photo-realistic quantum leap ahead of other games of its generation is a silly expectation.
Plot, story and immersion are down to the writing and do not have to have the limitations of computing power.
Given The Witcher's rich literary heritage, it is reasonable to expect high writing standards.
I hope for a journey alongside:
- Mass Effect (series)
- Baldur's Gate (series)
- Dragon Age: Origins
- Fallout 3
- Red Dead Redemption
Frankly, if the game would not be out of place alongside the above list, I'll be very happy.
Further expectations:
I'm expecting some bugs, because the game is huge.
I'm not expecting every side quest to be writing genius, in a game this size there will be less optimal 'fetch quests'.
In short, I'm expecting several hundreds of hours or entertainment over the coming months.
There are few enough games of this calibre to enjoy, you won't catch me whining about what it isn't, I shall be enjoying what it is.