* The Back Button (leftmost) -- the operation of this button is context sensitive (Am I going back a web page, back to the previous app? It depends on how I got to where I am now.) and it is so unfortunately right beside the backspace button in the landscape keyboard. This wouldn't be a problem for a physical button, but since it's touch-sensitive it's very easy to brush by back and lose all the form data you just entered on the webpage.
* The Menu Button (center-left): Hidden functionality is a bad idea. One of the nice things about the iPhone is that it's very rare the application has a capability that you cannot discover by looking at the contents of the screen. Android, on the other hand, routinely hides functionality in a menu. Worse, the type of functionality hidden is different in every application. You will never be able to guess where the "Accounts" menu button is going to be without looking at it.
* The Home Button (center-right): I have no problem with this button aside from its touch sensitivity.
* The Search Button (rightmost): On iPhones, we know this button as "hit the home button twice."
Re: the trackball -- it's because they don't have long-click precise targeting for the cursor on Android phones like they do on the iPhone.