I can't speak for guguy, of course, but the Sony gets about 90~95% of it for me -- my primary interest is in reading, though, so I don't particularly miss features such as annotations or searching.
What's it lacking, for me? I think the biggest deal is some of the quirks of the OS/Apps, no folders, no "go to page," etc. Though I expect someone will figure out how to change those from home before too long.
I would like a slightly larger display, but not too much larger, I like the overall size of the device for reading purposes.
A built in front-light that I could turn on only when I needed it is about the wildest want I have on it (I know it would hose the battery life, but it shouldn't be too
bad, what with the availability of low-power LEDs -- so what if I have to recharge it after 2 weeks if I use the light much, that's still not that burdensome to me).