Why does the N800 have a unibutton and a hidden button on the top? The 770 had three separate buttons on the top. The left button is now in the middle on the N800. The rocker switch (press left, press right) is now split into two buttons, on left and right. The power menu button on the 770 was arguably too easy to press, so I count the hidden button on the N800 an improvement.
But to merge the two buttons into one unibutton which is practically impossible to distinguish?? Why? The only way to distinguish between the buttons is to slide your finger back and forth a few times, trying to feel the subtle slope from the left to the middle and back down on the right. Only then can you take a guess at which button your finger is on.
Going back to the 770's buttons would be an improvement. Let's hope that the N830 (or whatever) makes that change.