A big problem on Netflix is that they don't use the original poster or description for movies, instead coming up with their own. I find that these generally don't do movies justice.
I remember reading that they have an algorithm that picks the "best" (colorful, cinematic, attention grabbing...) picture to show in the UI from the content itself. That is why sometimes the poster used represents a very minor character instead of the main lead.
Similarly, I'm not sure if I like that they play a short scene of a movie when you hover vs. showing the original trailer. Sometimes I like to watch familiar favorites but they just show me one short scene and it doesn't really draw me in as I had hoped.