Brother set up my aging mother with Roku and she loves it. Can access Netflix and Amazon Prime (both free and pay per) etc...keeps her quite busy. The speed and quality depend, largely, on your gear and service I suppose, but I've sat and watched stuff with her and think its as good as putting in a DVD.
Streams very well with a single bar of wifi
Streams services I use occasionally or subscribe to Netflix, Pandora and Vudu.
I really like Plex for for my own media
Dislikes:
Does not use Youtube by default
Not as smooth as Apple TV for personal media - pics videos etc.