I'm running 1920x1080. They're definitely squished. But yeah, it's not a ton.
Just looked through the code a bit, used the Welo view since I know that one looks squished to me. I have no experience with skinning, but it looks like this is where the poster is displayed.
Code:
<control type="image">
<posx>0</posx>
<posy>0</posy>
<width>160</width>
<height>216 </height>
<bordersize>8</bordersize>
<aspectratio scalediffuse="false">stretch</aspectratio>
<fadetime>200</fadetime>
<texture background="true" diffuse="shade/posterdiffuse.png">$INFO[Listitem.Icon]</texture>
</control>
216 / 160 = 1.35
US Poster sizes:
* One sheet, 27 inches by 40 inches (686x1020mm), portrait format = 1.48148148
* Bus stop, 40 inches by 60 inches (1016mm x 1524mm), portrait forma = 1.5
That's a pretty significant difference. I also see it's set to "stretch" which would cause it to squish since the vertical is smaller than it should be.
For comparison mini wall, which I use, has a size of 140 / 100 = 1.4 which is closer, but still squished a little. Also the "Poster list" view uses 320 / 220 = 1.45 (closer still).