I am seeing a lot of chatter from reviewers that the game is not so intensive on hardware as originally thought. That's always good , right?
The performance is awesme to say the least. I was coming directly from GTA V, which was already a dream come true in terms of performance versus graphical fidelity. Rockstar polished the game to a rare diamond and I didn't expect the same amount of polish from The Witcher 3. Surprise. ^^
Have added a GTX 970 since playing DAI, and I play The Witcher 3 on "ultra" with a few exceptions ("high" for shadows, grass density and foliage distance) in 1080p, antialiasing on, anisotropic filter at 16x and in most areas I average around 60fps. That's amazing!
Of course there is something to be said about a rumored downgrade and that consoles are at fault. CDPR already openly admited that they had to scale the game back in many areas, but the reasons for that are not solely the consoles. The version of 2013 was no fake and ran in real time on a pc. Yet the world was not complete back then (thus smaller and easier to handle), lacked dynamic weather and a dynamic day-night-cycle. When they added all this, performance took a hard hit. According to CDPR keeping the old lighting system with the new features would made the game almost impossible to perform on an acceptable level.
Console specifications did play a role in this, obviously. In 2013 they had no idea how slow the new generation would really be and were a bit shocked when they found out. Of course from a monetary point of view - and keep in mind that CDPR and their publisher are a long way from the league of Bioware and EA in terms of budget, market power etc. - it simply makes no sense to develop two or more different versions of the game. At that point, consoles became their focus. Maybe even before I guess. Consoles is were the money is, it's a simple truth.
In the end though, PC still is the best version in terms of graphics. Not only because of the possibly higher resolution and better antialiasing, but also in general. Many options, like foliage distance and grass density are scalable. The PC is the only platform capable of running the maximum of this scale. The "ultra" settings are unique for pc and the console version matches the "High" settings on PC. The PC also got some Nvidia gamework features, like HBAO+ for ambient occlusion and hairworks for...well...hair. ^^
In the end...looking at the game...and let's for a moment assume we wouldn't know anything about a downgrade...it looks jawdropingly beautiful. Console players say it's the best looking console game to date. And on PC there are also not many games that pair a multi-region open world with such a level of graphical fidelity.
So...that's all the information I was able to gather over the last few weeks / days as well as me actually playing the game for more or less a dozen hours now. 
I agree with many other players, that the game is something of a dream come true. The amout of detail found in this world makes you believe that in Poland, the days were 72 hours long. The partly empty, bland and generic maps of DAI are no match and according to many you wont find anything that could be considered "grinding" in The Witcher 3, yet still 100 hours seem to be a realistic amount of time we'll spend in it.