There is a menu, but it requires very little navigation. I wrote down a set of directions for my mother, and she is now able to use my console to play her movies. There is also a remote control you can purchase to avoid hassling with the game controller.
Most importantly, you can sign her up for Netflix (less than $10 a month), where hundreds of movies will be at her fingertips. Accessing Netflix over the PS3 is extremely simple.