The Steam Deck OLED improves much more than its screen

This is the best coverage of the new Deck that I’ve seen yet.

Upgraded:

7.4" OLED HDR screen with a 90hz refresh rate and 600 nits brightness (old screen 7" LCD with 60hz refresh and 400 nits brightness). Touchscreen accuracy and responsiveness is reportedly improved.
Longer battery life. Improvements to software and hardware are supposed to increase the battery life by 30-50%. New battery is 50wh vs original 40. Original decks will see some of this improvement thanks to software/bios updates, but not as much as the new Decks. The new Deck charges faster as well, charge from 20 to 80% battery in 45 min.
6E wifi module for improved wifi speed.
Dedicated bluetooth module, allowing better audio quality over bluetooth and the option to wake the steam deck from a bluetooth controller. Will also support more controllers at once for multiplayer.
Faster RAM, 6400 MT/s vs 5500 MT/s on original.
Supposedly more repairable.
New carrying case, more compact (but probably less protective).

Prices:

$649 - 1TB

$529 - 512GB

$399 - 256GB

For a limited time, Valve will sell a special deition 1TB OLED with a translucent shell for $679, only in the US and Canada. Expected to sell out quickly.