It's and interesting history more than anything else. He has been around for a while, I have to give him that.
But as for the idea that a smartphone will be enough for most people, I'm not sure. The idea is good, but I think we're probably ten years away from it in the rich world, just because the combination of display size and battery size isn't there yet. Given a rollup or foldup display and a couple of weeks battery life in a cellphone, then it'd be great for a whole range of things, not least reading books. But right now you plug your netbook (display) into phone (network) and brick-sized battery (battery life), hand the whole lot to your assistant (portability) and you're ready to roll.
I've tried reading books on my laptop, but it's much harder than I'd like - I have to lie on a flat surface so the laptop can sit next to me with the display rotated to portrait, and even then the pape-turning is annoying, there's no comfy way to turn pages.
My metric right now is page-turn ratio: how much of my reading time is spent waiting for page turns. With paper books is under 10%, with a Sony 505 it was over 20%. That is enough to be annoying, and make me want something with a bigger screen and faster page turns. So I'm not buying a replacement for my 505 until I can get something significantly better. Even A4 (two A5 pages) with the current one second page turn would be ok, but surely it's going to be faster than that.