I've dipped my toe into the pen input tablet world a few times (often unimpressed), but recently committed to a new iPad Air with the latest Pencil Pro.
I write on paper and whiteboards every day for software design and todo lists and just general musing. But recently had an itch for the advantages of digital. And I'm really happy so far. A lot comes down to the app you choose and how convenient the UI/UX is, but the killer features I'm going to hate living without:
1. Infinite canvas. Never have to truncate a sentence or messily cross the spine or flip a page. So much context, I just pan and zoom to what I want to focus on.
2. Rearrange rather than rewrite. Long-press turns my pen tool into a lasso, then I drag however.
3. Very productive erasing. Using the new squeeze gesture, my pen is instantly an eraser and only takes one pass.
In my opinion, nothing beats a whiteboard for conversations about software. It's one of the biggest losses from the pivot to remote work. My ultimate goal is to bring convenient whiteboarding to zoom calls. But so far I'm really enjoying it in place of the pad of paper that's on my desk.