I suppose there are roughly three uses for a screen
- watching video ("Watching TV")
- reading/interacting with internet
- playing games
If you watch netflix, lovefilm, DVDs, whatever, that is "watching TV." I only watch rugby "live", drama, documentary and movies are watched when I feel like. I have ten or so things on series record. The sky box is connected to the internet and can downloaded things (from terrestrial or Sky channels) that I miss. (DD and DW do watch some TV "live" though.)
I only want to watch video in 1080 line HD on a giant screen with several hundred watts of surround sound including a dedicated subwoofer. Tablets, laptops, computer monitors are inferior. (I do have a computer attached to the TV, in addition to the Sky box, but seldom use it other than as a Freeview recorder to supplement Sky, or as a DVD player for DD/DW stuff.)
For internetting, I use a 22 inch monitor, in portrait mode. The TV screen would be crap at this, a landscape mode monitor would be OK but inferior, a tablet would be inferior due to relatively small screen and no proper keyboard.
I don't play games.
I don't own a smartphone or tablet, and feel sorry for people who regularly have to use such puny devices for any screen-based activity. (I do own a netbook which is my holiday screen, and DW smartphone and tablet were useful when hanging around a hospital for a few days.)