The latency would make it tough for anything other than word processing (and even that would be a bit annoying).
What I would really like, however, is a monitor-sized Sharp Memory LCD display, as made famous by the Pebble. The colour displays are things of beauty. The colour gamut's not brilliant, but they refresh instantly, consume practically no power, and look great. With the backlight turned off, you get an interesting metallic sheen that looks like no other display on earth.
Even the monochrome ones are really cool. I have a development kit where the display can show white and silver --- like, metallic, reflective silver, which you can (just about) see your face in.
Alas, they don't make them much bigger than watch sized.
Edit: This was with a black and white display. Depending on how the colour displays work, avoiding latency might not be possible as easily.
We wanted to make eink displays with touchscreen controls for videoconferencing but the latency isnt great.
Recently, Apple bought the Taiwan fab plant where the old mirasol displays were made, which had been transferred to AU Optronics. But a fab is a fab is a fab so it doesn't mean they're making mirasol displays there.
Liquavista is another crapshoot, spun off in 2006, made huge pronouncements at shows, told us they would be production ready in 8-12 months back in 2010 and then shuttered in Dec 2010. Then layoffs, then Samsung, now Amazon. No clue what their real status is now.
In other words, doing demos is doing demos. Commercially available production ready product is a different story completely.
http://www.cnet.com/uk/news/kyobo-mirasol-color-e-reader-deb...
http://www.pcworld.com/article/259582/how_to_use_a_kindle_dx...
But I will put up with that -- the "good" of it being easy on the eyes trumps the "bad" of latency issues.
Though, let's hope the technology matures and this problem is solved to some extent.