WOW.. I am blown away by the K4.
Here is my quick take (even though you didn't ask for it!)
I wasn't sure about the new style and color. IMHO, The pictures made it look like the sony PRS300. In person i find it fantastic. The images and pictures do not do it justice. You should really hold it in your hands before you pass judgment on the color or case design.
Its got a very subtle 'kindle' on the top bezel and a not-to-advertisementy 'Amazon' on the back.
It has a very nice feel in the hands. The back has a nice 'rubbery' feel to it that the front bezel and sides don't. Its not as rubbery as some of the newer blackberry's... but it has a very 'soft' feeling in the hand.
It's almost too small... but a case will make easier to hold (IMHO again).
The page buttons have a very nice feel to them. They don't click but they are not 'soft'. Amazon nailed the 'tactile' feel i wanted. (I hated the button click on the K2). The menu buttons are small but still easy to get to.
The screen is different then the K3. Even my 11 year old non-techie daughter noticed how different it was then her 4 month old K3. It 'seems' to have better contrast and a brighter (less grey) screen.
HOWEVER! It does have a thin black bezel/inlay around the screen (you can
see it in this picture). Adding a black boarder to the screen can give the appearance of better contrast. My daughter swears its better then her K3, I think its better then her K3 (and WAY better then my K2).
The speed increase over the K3 is noticeable.
As for the keyboard... I found it very easy to type in my wifi password. Thats probably the last time i'll use it
.
The only fault i can find, and its really not a fault, is that it might be tooo thin and light
. Its just my opinion... but a case will make it fit in the hands better.
Overall its an amazing upgrade (just ask my daughter.. according to her, the K3 is sooooo outdated).
It will be interesting to hear what people think of the touch...