I am kinda waiting for the DX to drop in price. I really want that bigger e-ink screen, but it's not worth $379 to me.
I find the smaller E-ink screens a great fit for comfortable reading of fiction, or non-fiction prose like biography or history, where one doesn't need to skip around much, and the font size adjustment may come in handy.
Note that my experience is on a 2010 vintage DX with no WiFi - it is limited to 3G on Amazon's dime. In Europe that's only Wikipedia and the Amazon store.