Performance has been shown to be significantly better in certain games, which makes sense given the much more efficient and thermally improved APU, and the faster RAM. Plus the more energy efficient screen, giving more TDP headroom.
Also, I would guess that performance will be even more improved with future firmware and drivers, plus the possibility of maybe being able to overclock the chip and/or increasing the TDP, getting better performance with the same battery life as the LCD.
And so many other changes; improved thumbsticks, trackpads and shoulder buttons, plus wifi 6e, improved BT, separate wifi and BT antennas, larger & quieter cooling fan, improved disassembly and upgradeability/repairability.
Also, the framerate doubling should make a big difference, being able to run games at 45fps internal rendering, but getting 90fps picture.