I've been playing Xenoblade Chronicles Definitive Edition Switch 2 Edition (love the title xD). Since it's one of my favourite games ever, I started a brand new playthrough. I'm at Tephra Cave (first visit) right now.
60fps are nice and make the game feel more fluid. It's not locked 60 though, there are some dips here and there. But those are very minor and far in between. Both cutscenes and gameplay run at 60 btw. There are some remasters where cutscenes are kept at 30, but not this one.
Something I've not seen people talk too much about is rumble. They have implemented HD Rumble in every cutscene and... it's great! Explosions and hits come from the right or left joy-con depending on where they happen on screen. Intensity also varies depending on what's going on. It's not mindblowing or anything, but this makes cutscenes more immersive.
Heart to hearts are now voiced acted. This is huge, because they were just text boxes before... so they have bring in the old 2011 cast for these. I've just watched the first one with Fiora and Shulk at the park, but despite them being 15 years older now, they still sound like the characters and they have put quite the effort into sounding like their younger selfs.
Sadly, I haven't unlocked the new content yet (mainly the Ether Glider) but it seems like it will be of big help when backtracking for side missions.
The bad stuff: visuals are mixed. For the most part, the game way looks WAY better and crisper than on Switch 1. No surprise there: it was 720p docked and on handheld it could go as low as 360p. So SW2 in both docked and handheld is leagues beyond that. However, whathever they did with XCX Switch 2 Edition is back here. On dock it's not THAT noticeable, but in portable mode particle and lightning effects and also distant backgrounds can become quite a mess if you pay attention. Here's an example: first pic is Switch 1 docked, second is Switch 2 docked and third is Switch 2 handheld:



As you can see, the laser effect is messed up on Switch 2 (especially on handheld). This happens with everything that casts a similar effect, like the beam of light coming from the Monado, the water moving in the initial battle between Bionis and Mekonis, etc. Background elements are a similar history: distant objects can become "messy"... like the textures blend together weirdly. It's unfortunate, because if they fixed this the upgrade would be perfect.
All in all is certainly an upgrade on every front... but they really need to take a look at whathever upscaling solution they implemented here.