Okay now I've played with it a bit I can say a bit more.
I love the how light and tiny it is! I could hold this with no problems. I love the replacement of the 5-way button. The middle is perfect for two hands to navigate each side.
I do not like the new refresh so I went back to the old way. Black flash is better for me. The new way makes my eyes goes weird but I am the kind of person who got sick when she set her Sims 3 game to 30fps. I can't even play sonic games so keep that in mind. The black flash does not have the same effect on me.
The more I stare at it, the darker the text looks. So it takes some getting use to so unless I have my K3 in front of me which is perfect in display I notice it less on the K4.
My K3 background is a very light tan almost white and my K4 background is a grey and my Pocket Pro background is a light grey. The Pocket Pro has a lighter background and is a Vizplex.
The text on my K3 is black as black can get. The text on the K4 is near black when in bold or a very dark grey in non bold. The text on my Pocket pro is light to medium grey.
Now I know I can use a heavy font or blacker font and that will help. When I switch to the sans font on the K4 it looks almost black but the default font does not.

The text is a very dark grey on a greyish background.
The keyboard is something you will have to experience for yourself. The biggest downside is no delete button you have to use the the delete key on the keyboard to go back a letter. This is one thing I find annoying. The Keyboard isn't so bad but when you are use to a QWERTY style it will take some brain retraining to find the letters faster.
The navigation that felt clunky on the K3. The K4 does not have this feel to it. It's seems to be faster to me. I think this is due to the 5-way being in the middle not to mention faster processor.
If you one to type notes alot you want to wait for the Touch or stay with your K3.
The browser is faster and seems to load faster with my connection. I had it freeze already on Dropbox and had to a restart. It does this to me on my K3 but other then that it's pretty much the same as the K3 but a bit faster.
Oh I forgot one! I love the back button is finally out the way! I can't tell you how happy that makes me! That is probably the best improvement on here.