I've got big hands, I'm 6ft 2" and loved the duke controller (the big controller) of the original xbox but even so I find the gamepad too large. It doesn't sit well in my hands especially playing an intense game. I hate the lack of analogue triggers. It never needed to be this big. Somthing like the pro controller with a touch screen at the back would have been ideal not something the size of a tablet. The money they saved doing a small gamepad should have been put towards a 28 or 32nm fabrication process for the gpu and cpu so instead of running at 1.25ghz and 550mhz they could have run at 2.5ghz and 900mhz (and faster ddr memory) thus making the wii u easily more powerful than 360 and PS3 and not have the embarrassment of being beaten by 360 and PS3 games.
The gamepad was ill judged from a gaming viewpoint.
Put it this way I bought Sonic Racing Transformed for the wii u and realised I loved the game but didn't quite get on with the gamepad and lack of analogue triggers. So I got the ps3 version when it was going cheap. Not only did it play better thanks to analogue triggers but it was higher resolution too and looked much better. Also much better sound support.
Although the performance level of the wii u is now set in stone the gamepad can be replaced with something much better.
