Neither.
The Wii U's major failing is the market comparison with the PS3/360. Your ordinary uninformed consumer walks up to the shelf and sees three HD consoles. The Wii U has the highest price and the fewest games. Bam: poor sales. And there's really nothing Nintendo could do about this, either.
Arguably Nintendo has failed to sell the Gamepad as a revolutionary way to play games, but even there I don't think so. Even if Nintendo had been pushing multiple major titles a month for the whole first year in a historically unprecedented fashion, the Wii U would still not look particularly appealing until the PS4 and XB1 launched. Even with titles, it's still expensive and lacks a used game market.







