It's pretty bad. So far I've been trying to tweak my UI since release. I tried 150% and everything was HUGE.

Temporary solution:
>Go To System Configuration
>User Interface Size: 100%
-This will restore the names to normal size but names only
>Go to Default UI Size and set to: 120%(or whatever you're comfortable with) then select "Apply All"
>Manually resize anything that you want bigger or smaller than 120% by pressing R3. This means every single menu box
>Tweak Hotbars or whatever and done.
>End result should be a somewhat similar screen to your 3.x version but there are drawbacks that can't be fixed right now including:
-Dialogue boxes smaller
-Tooltips smaller and at a different area of the screen.

I hope this helps