If you had any doubts about how well Dark Souls would run on the Switch, there's some good news.
Firstly, the Switch handles Blighttown substantially better than the last-gen versions. If you remember any technical tests from the last gen, the PS3 and 360 could plunge to frame rates in the low 10s - even just turning around at the bonfire.
The Switch handles that substantially better, although not perfectly smooth. The frame rate drops are most noticeable when playing in handheld, but for the most part the performance is reasonable.
There is a dynamic resolution used, which helps the Switch maintain performance. As Digital Foundry measured, handheld performance can drop to around 20fps at the worst elements, as can be seen with the Red Wyvern above.
The bad news is that the audio quality is horrifically compressed. It's noticeably worse than the 360/PS3 versions, sounding muddy and lacking any clarity at all. You'll notice it most if you're playing through TV speakers or headphones, particularly when voices are playing.
Digital Foundry also noticed that frame pacing issues - a problem when the game first launched - are present in the Switch version. It's a byproduct of the underlying engine, and if you want the absolute best experience on console the Xbox One X is the only way to go.
But is Dark Souls a playable handheld experience? The answer is yes, although it's worth knowing where the caveats are. Still, if you played Dark Souls when it first came out and put up with the nightmare that was Blighttown, you should be able to enjoy the Switch version just fine.
Real shame about that audio, though.