This was an upgrade from the first Kindle Oasis (8th Gen) for me, and I bought it for the novelty of being able to adjust the colour temperature. It didn't occur to me until I opened it that the screen is larger, so that was a nice surprise. It isn't so big that it is a problem, but the 8th gen version was practically weightless, and felt like I has holding thin air - particularly without the cover (which was also supplementary battery). This new one has slightly more heft, and really needs a cover - even though it is no longer a batter - because the texture without a cover makes it feel like it is going to slip out of your hand.
I didn't get the version with cellular connectivity this time, as I can tether to my phone for when I need to sync it - the amount of data isn't so big that there is ever any danger of using it all up, and of course I have the wifi at home or office. I tend to buy books when I stumble over them - not as I need something else to read, so I always have some in backlog.
My workflow is turn off airplane mode, download everything I haven't read, turn on airplane mode. Then when I've read through a couple of books, or have bought something else - repeat the process. This means that connectivity is OFF for the vast majority of the time, and whilst this device appears to use battery slightly faster (but only had it a couple weeks), it still lasts effectively forever. I've never had battery anxiety with the 8th Gen, and I don't imagine I will here either.
It would have been good to have the charger move to USB-C .. the Kindle was already the last thing I had that still needed the micro-USB, so to upgrade and still have it is strange, but I guess the Kindle isn't going to benefit greatly from the more rapid charging, so they figure - why spend the extra.
I could have lived without the upgrade, but still pretty happy with the purchase.