I think overall the UI is really well made and I don't have any serious grievances with it. I think the taskbar looks clean and efficient, but there is always room for improvements on small details, so here goes!
- Unit stats instead of a description (if that even counts as a UI issue instead of an info one), as well as more specific descriptions of what each level of veterancy does
- Available weapon slots left in the squad, especially useful for USF
- A way to see all weapons held by squad. As it stands, if, for example, you have a BAR and bazooka equipped on one squad, the squad icon will only show the weapon picked up first
- Shermans need an easy to see indicator of whether they're using HE or AP shells (invisible to enemies)
- Custom hotkeys, though I don't know if you count that as UI
- Being able to turn off territory markers in-game
- Being able to adjust the overall size of the taskbar like you can do in replays
- Maybe some sort of toggleable indicator of where close, mid, and long distance modifiers take effect for each unit (think: more detailed version of radius snipers get)
- Kubelwagen really, really needs a hold position button. I hate when it rotates or chases on its own and loses its suppression
Here are some of the small details that are currently in that I really appreciate it.
- Circle becomes larger or smaller depending on range when using. barrage abilities on artillery
- Range circle around snipers
- Ability to fire at only tanks for certain units
- Very easy to access any unit at any time because of the upper right hand corner icons
- Veterancy progress
- Descriptive icons on tactical map