The original Wii U GamePad had slider pads

As with any consumer product, the Wii U has gone through revisions since it leapt off the drawing boards at Nintendo's Kyoto HQ.

One of the features that has undergone the most change is the GamePad itself; as you will no doubt recall, the first publicly-announced model had slider pads like the one seen on the 3DS handheld, as well as other cosmetic differences.

Toki Tori 2 developer Two Tribes is incredibly pleased that Nintendo decided to revise the controller, and has revealed on Twitter that the first version was less than satisfactory.

Twotribes1
Twotribes2
Twotribes3

[source twitter.com]