I caved and got a Switch OLED, since most of my playtime is handheld and the battery life of my launch Switch has gotten to be horrendous. It's definitely a no-brainer if you're a first-time Switch buyer--it feels a lot more premium and the screen provides a noticeable difference in the quality of the visuals. I've had fun going back to old games and seeing how they look on a display that pops a little (a lot) more. All of the other non-screen and non-battery improvements are nice-to-haves, I'd say, but not essential if you're looking for more reasons to upgrade. The audio does sound fuller, but I realize most people use headphones anyway. So, meh. And the kickstand makes tabletop play a lot more appealing, yet I can't help but wonder why they didn't design it that way in the first place.
The Joy-Con, meanwhile, are showing their age and probably the least-premium feeling part of the Switch at this point. I think there's a lot they can do to improve them for whatever the Switch 2 ends up being. Everything feels too click-y and the analog sticks have their obvious problems. Plus, "HD Rumble" has started to feel a lot less impressive after adjusting to the DualSense for the past year.
All in all: Solid hardware iteration from Nintendo, if you look at it from the standpoint of this being a GBA SP, DS Lite, New 3DS, etc. It's a worthy addition among that lineup.