My T430 and T510 are great, but the one T440 I dealt with I wouldn't have even delivered to the customer except he's one of those guys who carries a wireless mouse around with him.
On the T440 they made the touchpad larger and eliminated the separate buttons - instead you just pushed down on the touchpad in the appropriate corner, and yes the corners would sink, and the mouse pointer would move because you're still touching the touchpad. In my limited time using it accurately clicking anywhere was basically impossible. Most of the changes were reverted on the Tx50 generation, and you can actually replace the T440 "buttonless" touchpad with one from the T450. That at least gets you the buttons at the top of the pad.
