Other than battery level, I don't personally think that anything else is needed.
My perfect display would just give power settings, battery level, and be the size of an old Casio digital wrist watch.
By comparison to your old unit, this is the current Panasonic display, as fitted to my e-Race P
The annoying thing about this display, which frequently gets mentioned by other owners, is that it is all too easy knock the power button whilst trying to change settings, when wearing gloves.
The following highlights one of the reasons that I hate Nyon so much.
Besides being too big and useless for e-mtb use, it also has a very annoying habit of changing the menu settings when used over bumpy terrain. This issue has also been raised other users, that ride off road. When the display does it, it is almost impossible to reset the display whilst riding.
In the clip, the display had already changed before setting off, and I didn't notice until the one minute point in the clip.