Yes, this is definitely true. I mean it looks somewhat worse than native Bing now, but who knows what the future brings. I should also rephrase ‘horrible’ to ‘not like bing maps’.
One thing they seem to apply is making every second pixel black, thus making the image storage size smaller in terms of MB and this helps of course streaming it in. When you zoom in, they always have this rasterized look in addition to being of lower resolution than native Bing maps.