I was surprised to see Doom 2016 running stably on the Switch, so for it to run The Witcher 3 at all is nothing short of miraculous. Nintendo UK recently released 25-odd minutes of footage showing the Switch port of Geralt's latest in action, and while it's noticeably trimmed down, it presents pretty well given the circumstances.
If you've ever cranked down FPS-hogging settings in a PC game, you've already got some idea of where CD Projekt Red would have looked to make cuts in order to get this thing running on the Switch, which in terms of raw power, is about a PS3.5. Lighting is harder, there's a bit of pop-in with textures and npcs, textures are less detailed (especially on the ground and environment), and effects like rain and fire aren't as flashy. That said, the frame rate seems pretty stable, characters look sharp in dialogue scenes, and the draw distance looks decent. Perhaps most importantly, Geralt is still handsome. Here's hoping the load times aren't that bad. Surely they can't be any worse than Bloodborne's.
For reference, I'd say the Switch port of The Witcher 3 looks a bit better than the PS4 port of Dragon's Dogma - which originally came out on PS3 - and that ain't bad. I might even put it up there with a mod-enhanced PC port of Dragon's Dogma. Besides, the sheer novelty of playing The Witcher 3, one of the best and biggest RPGs of all time, not only on a Nintendo system but on a freaking handheld ought to make up for a lot of graphical sacrifices. It's hard to get upset about foliage quality when you're slaying monsters on a plane.
Check out our Witcher 3 Nintendo Switch preview for more details on how the RPG handles the jump to handled.