Voyagers, 80x and Pendolinos have the displays in a separate bodyside hole (in the door in the Pendolino's case). They often steam up and seem unreliable possibly as a result of that.
They are a bit big on the Stadlers for some reason; fortunately other stock doesn't replicate that. More usual is that they sit in the space that would be used by a window opener if there was one, so you don't tend to look out of there anyway.
Displays, in general, is one of the things that I think the Civities get very right. They are easy and the interior TFT panels lay out the information in a clear, simple to understand way, while the exterior ones have big, clear letters and clearly display the coach letter. The only problem they have is that you can't read the outside ones in direct sunlight, but that seems to be an issue with all trains, and buses as well.
As for them taking up window space - they don't really, at least not in a meaningful way. The photo on Wikipedia illustrates this very well- they're a long way above head level for almost all passengers, and for the few that might find their view obstructed, there are plenty of other seats with unobstructed windows.
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By Superalbs - Own work, CC BY-SA 4.0)
Picture shows the interior of a Northern Class 331.