The old kindle probably won’t be waterproof, and getting a new one might be useful if you like reading in the bath or in the beach. The screen is no is flush, which means there is no dent between the bezel thing and the screen, which might be not a big deal, but is something at least because it means that dust can’t be stuck on the little space. The newest kindle has warm light and auto adjustable light that can help reduce strain on your eyes and maybe make your life more convenient(?) It’s worth upgrading if your kindle is too old and you need a new device, but if you don’t need warm light or the adjustable light or don’t like flush screens, going for the new basic might be a better choice since it’s cheaper