I'm surprised by all the negative comments, I actually find this concept pretty intriguing, especially that you can flip it around so its a "normal" 480 X 800 display phone (if you had to open it to use it I wouldn't be interested). At least its something beyond the "black slab" which is all we seem to get now.
The lack of a 4G radio is probably an attempt to keep the device as thin as possible, but it could also be a leading indicator of Kyrocera's engineering skills (they probably haven't worked at all with WiMAX chips), and if that's the case I'm concerned about the speed of software updates, the hooks into Android to make those dual screens work being buggy and various compatibility issues.
I'm an EVO 4G owner and I love my phone, but honestly the "4G" part of it is becoming a joke to me. I live and work in downtown Chicago and rarely can get a usable 4G signal (the coverage map means absolutely nothing, I've decided). Its gotten to the point that my 4G radio is permanently off and I only use it in a couple of spots I know it works and at airports when I tether my iPad. As a Sprint fan 4G has been a huge disappointment for me and has me seriously thinking about Verizon's LTE alternative. So the lack of 4G on this phone isn't a deal-breaker for me to check it out.