Yep, it's not a tablet. A tablet is a much better idea than the gamepad. It offers more functionality and flexibility while at the same time costing far less than the Gamepad + Wii U combo.
Makes you wonder why Nintendo wasted so much R&D on the gamepad when they could have taken that idea just a few steps further and made a tablet.
The other approach would be to utilize the millions of tablets already on the market for the system and not bogged down R&D with the gamepad. Sony and MS made the better decision in this regard by far.
Not from a developer's perspective. Or even a user's perspective honestly.
Just like Kinect - if I am Nintendo or MS and I want something supported full-stop, I am building my console around it. The Gamepad is not a tacked on piece of the Wii U, it is its central component.
Sony and MS will suffer from developers tacking on second-screen support as an after-thought. The Wii U can have games built entirely around utilizing the WiiPad.